Die Naturwissenschaften. Wochenschrift..., 12. Jg. 1924, 15. August, Heft 33.

DIE NATURWISSENSCHAFTEN

Z w ö lfte r J a h rgan g 15. A u g u st 1924 H eft 33

Zur Physik der Klänge.

Mitteilung aus dem Forschungslaboratorium Siemensstadt.

V o n Fe r d i n a n d Tr e n d e l e n b u r g, B e r l i n 1).

D ie A u f k lä r u n g d e r p h y s ik a lis c h e n E ig e n ­ s c h a f t e n d e r K lä n g e , in s b e s o n d e r e d e r K lä n g e d e r m e n s c h lic h e n S tim m e , t r ä g t z u r F ö r d e r u n g e in e r R e ih e v o n W is s e n s z w e ig e n b e i: d ie P h y s i o ­ lo g ie k a n n a u s d ie s e n E ig e n s c h a f t e n a u f d ie F u n k t io n e n d e r s p r a c h b ild e n d e n O r g a n e — d e s S tim m b a n d e s , d e s K e h lk o p fe s , d e r M u n d h ö h le — e in e r s e it s u n d d e r G e h ö r o r g a n e a n d e r e r s e its s c h lie ß e n , d ie P s y c h o lo g ie w ir d a u s d e n K l a n g ­ f o r s c h u n g e n m a n c h e A u fs c h lü s s e ü b e r P r o b le m e ih r e r A r b e it s r ic h t u n g g e w in n e n k ö n n e n . I n n e u e ­ s t e r Z e i t n im m t d ie T e c h n ik r e g e s I n t e r e s s e a n d e r K la n g p h y s i k , sie i s t b e m ü h t , d ie K l ä n g e d e r S p r a c h e u n d d e r M u s ik d u r c h L e it u n g e n o d e r d r a h t lo s in d ie F e r n e zu ü b e r tr a g e n u n d d o r t w ie d e r z u g e b e n , g e r a d e d ie s e te c h n is c h e n P r o b le m e s t e lle n a b e r h o h e A n fo r d e r u n g e n a n d e n S t a n d d e r F o r s c h u n g . S o lle n a lle p e r s ö n lic h e n F e in h e it e n d e r K l a n g f a r b e w ie d e r g e g e b e n w e r d e n , so m u ß z u n ä c h s t d ie E r k e n n t n is g e w o n n e n w e rd e n , w o r in d ie p h y s ik a lis c h e B e d e u t u n g d ie s e r K la n g e ig e n ­ h e it e n lie g t .

D ie p h y s ik a lis c h e n E ig e n s c h a f te n e in e s K la n g e s s in d b e k a n n t lic h d u r c h d ie I n t e n s i t ä t u n d d ie T o n ­ h ö h e d e s G r u n d t o n e s u n d d e r O b e r t ö n e b e s t im m t , w e lc h e d e n K l a n g b ild e n . I n t e n s i t ä t u n d T o n h ö h e d ie s e r T e ilt ö n e la s s e n s ic h a m b e s te n a u s d e m z e itlic h e n V e r la u f d e s D r u c k e s a n e in e r S t e lle d e s S c h a llf e ld e s e r m it te ln — n a c h Fo u r i e r k ö n n e n w ir d ie s e D r u c k f u n k t io n s c h r e ib e n 2) :

P == P Q - f P j sin co t -j- P 2 sin 2 co t + P 3 sin 3 co t + . . . . h ie r b e i i s t P 0 d e r m it t le r e A t m o s p h ä r e n d r u c k , P n s in d d ie D r u c k a m p J itu d e n d e r e in z e ln e n T e i l ­ t ö n e , (o — z n N i s t d ie K r e is fr e q u e n z d e s G r u n d ­ to n e s .

W i r w o lle n d ie s e n A n s a t z a llg e m e in a ls d a s K l a n g b i l d b e z e ic h n e n , a u f d ie G e w in n u n g d e s K la n g b ild e s z ie lt d ie e x p e r im e n t e lle K la n g p h y s ik .

S u b j e k t i v e K la n g u n t e r s u c h u n g e n , w ie sie v o n He l m h o l t z u n d St u m p f, a u f d e r e n F o r s c h u n g s ­ e r g e b n is s e ic h s p ä t e r k o m m e n w e r d e , m it t e ls R e s o n a t o r e n d u r c h g e f ü h r t w u r d e n , lie fe r n n u r e in e n b e d in g te n A u f s c h lu ß ü b e r d ie P h y s i k d e r K lä n g e , d a s m e n s c h lic h e O h r w ir d a ls I n d ic a t o r -

x) Ü b er die A rb e it w urde am 22. F e b ru a r 1924 v o r der D eu tsch en G esellsch aft fü r tech n isch e P h y sik u n d am 27. F e b ru a r 1924 v o r der D eu tsch en p h y s io ­ logischen G esellsch a ft v o rg etra g en .

2) D ie P h asen w in k el cpn können fü r unsere B e ­ tr a ch tu n g e n u n b erü ck sich tig t bleiben.

Nw. 1924.

i n s t r u m e n t b e n u t z t : s t a t t d e r p h y s ik a lis c h e n I n t e n s i t ä t s v e r t e ilu n g d e s K la n g e s e r m it t e ln w ir d ie T e ilt o n r e ih e so, w ie sie u n t e r V e r m it t e lu n g d e s O h r e s a u f u n s e r s u b je k t iv e s E m p fin d e n e in w ir k t , w ir m ü ß t e n a ls o u n s e re R e s u lt a t e in d e r W e is e k o r r ig ie r e n , d a ß w ir s o w o h l d ie A b h ä n g i g k e i t d e r G e h ö r s e m p fin d u n g v o n d e r T o n h ö h e a ls a u c h v o n d e r a u f d a s O h r fa lle n d e n R e iz s t ä r k e b e r ü c k ­ s ic h t ig e n . D e r G e d a n k e , d ie s e S c h w ie r ig k e it e n d a d u r c h zu u m g e h e n , d a ß m a n z u r K la n g f o r s c h u n g e in e re in p h y s ik a lis c h e , o b j e k t i v a r b e ite n d e M e t h o d e v e r w e n d e t , w u r d e v o n v ie le n F o r s c h e r n a u s g e b a u t.

B r i n g t m a n z. B . in d a s S c h a llf e ld e in e M e m b r a n , so w ir d d ie s e u n t e r E in w ir k u n g d e s K la n g e s e in e e r z w u n g e n e S c h w in g u n g a u s fü h r e n , d ie F o r m d ie s e r S c h w in g u n g w ir d e in m e h r o d e r w e n ig e r g e tr e u e s A b b i ld d e r e r z w in g e n d e n K la n g s c h w in g u n g se in . D ie a u f d ie M e m b r a n w ir k e n d e K r a f t , w e lc h e d ie m e c h a n is c h e S c h w in g u n g h e r v o r r u ft , is t P • F , w o b e i P d e r D r u c k im S c h a llf e ld a n d e r M e m b r a n ­ o b e r flä c h e F is t. E r r e ic h e n w ir e s n u n , d a ß d ie A m p lit u d e d e r M e m b r a n s t e t s p r o p o r t io n a l d e r D r u c k a m p lit u d e P b le ib t , so z e ic h n e t u n s d ie M e m b r a n d e n z e it lic h e n V e r la u f d e s S c h a lld r u c k e s a n d e r b e t r e ffe n d e n S t e lle d e s S c h a llfe ld e s a u f.

D ie T h e o r ie d e r e r z w u n g e n e n S c h w in g u n g e n le h r t, d a ß d ie M e m b r a n a m p lit u d e d a n n d e r D r u c k ­ a m p lit u d e f o lg t , w e n n w ir e in E m p fa n g s s y s t e m b e n u t z e n , d e s se n h in r e ic h e n d g e d ä m p f t e E ig e n ­ s c h w in g u n g o b e r h a lb d e s n o c h r i c h t i g w ie d e r ­ z u g e b e n d e n h ö c h s te n T e ilt o n e s lie g t . D ie F o r s c h e r , w e lc h e b is h e r o b j e k t i v e K la n g b ild e r a u fg e n o m m e n h a b e n , m u ß t e n a u f s t r e n g e D u r c h fü h r u n g d ie s e r B e d in g u n g v e r z ic h t e n , d a d a s H e r a u f s e t z e n d e r E ig e n f r e q u e n z e in g le ic h z e itig e s s t a r k e s H e r a b ­ d r ü c k e n d e r E m p f in d lic h k e it b e d e u t e t u n d sie d a h e r b e i V e r w e n d u n g e in e r o b e r h a lb d e s S p r a c h ­ g e b ie t e s lie g e n d e n E ig e n f r e q u e n z n ic h t m e h r in d e r L a g e w a r e n , d ie v o n d e n s c h w a c h e n S c h a llin t e n s i­

t ä t e n d e r m e n s c h lic h e n S t im m e e r z w u n g e n e n M e m b r a n s c h w in g u n g e n m it H ilf e ih r e r M e t h o d e n , z. B . S p ie g e lc h e n u n d L i c h t z e ig e r , a u fz u z e ic h n e n . D ie E ig e n s c h w in g u n g d e r M e m b r a n e n la g n o c h in n e r h a lb d e r a k u s t is c h w ic h t ig e n T o n g e b ie t e , d ie K la n g b ild e r sin d d u r c h d ie s e le k t iv e B e v o r ­ z u g u n g b e s t im m t e r T e ilt ö n e v e r z e r r t . M a n h a t e in e R e ih e v o n M e t h o d e n e r p r o b t , w e lc h e r e s o n a n z ­ fr e i s in d u n d th e o r e t is c h e in w a n d fr e ie R e s u lt a t e lie fe rn , d o c h w a r ih n e n k e in e r h e b lic h e r E r f o lg b e s c h ie d e n , d ie E m p fin d lic h k e it d e r M e t h o d e n w a r zu g e rin g .

87

662 Tr e n d e l e n b u r g: Z u r P h y s ik der K lä n g e . T Die N atur- [wissenschaften I c h h a b e im F o r s c h u n g s la b o r a t o r iu m d e s

S ie m e n s - K o n z e r n s e in e M e t h o d e a u s g e a r b e it e t , w e lc h e b is zu se h r h o h e n T e ilt ö n e n g e t r e u e K l a n g ­ b ild e r lie fe r t . I c h h a b e d ie a k u s t is c h e n W e lle n z u m S t e u e r n v o n e le k t r is c h e n S tr ö m e n b e n u t z t u n d d a s K u r v e n b i l d d ie s e r W e c h s e ls t r ö m e im O s z illo g r a p h a u fg e z e ic h n e t . D ie M e th o d e w u r d e so a u s g e b a u t , d a ß d a s o s z illo g r a p h is c h g e w o n n e n e S t r o m b il d u n m it t e lb a r d a s K la n g b i ld e r g ib t , d ie S t r o m a m p lit u d e e n t s p r ic h t im g e s a m t e n S p r a c h ­ g e b ie t d e r D r u c k a m p lit u d e a m S c h a lle m p f ä n g e r . W ü r d e m a n z u r U m s e t z u n g d e r a k u s t is c h e n V o r g ä n g e in e le k t r is c h e e in g e w ö h n lic h e s M ik r o ­ p h o n v e r w e n d e n , so w ä r e d ie F o r d e r u n g d e r k u r v e n g e t r e u e n K la n g a u fn a h m e b e i w e it e m n ic h t e r fü llt , d ie M e m b r a n d e s M ik r o p h o n s — w e lc h e i n ­ m it t e n d e s S p r a c h g e b ie t e s a b g e s t im m t is t — w ü r d e d u r c h R e s o n a n z e r s c h e in u n g e n V e r z e r r u n g e n h i n ­ e in b r in g e n ; ü b e r d ie s b e s i t z t d a s K o h le n k ö r n e r ­ m ik r o p h o n n o c h e in e w e ite r e , se h r s t ö r e n d e E i g e n ­ s c h a f t : d a s M ik r o p h o n h a t e in e n e n d lic h e n S c h w e l­

le n w e r t, so d a ß es a u f se h r k le in e I m p u ls e ü b e r h a u p t n i c h t a n s p r ic h t . D ie s h a t z u r F o lg e , d a ß v ie le F e i n ­ h e it e n d e r K l a n g s t r u k t u r n ic h t e r f a ß t w e rd e n .

M a n k ö n n t e a ls E m p fa n g s s y s t e m e in e n E m p ­ f ä n g e r v e r w e n d e n , w e lc h e r o h n e R e s o n a n z e r s c h e i­

n u n g e n a r b e it e t , z . B . e in e I o n is a tio n s s t r e c k e , w e lc h e d u r c h d e n S c h a lld r u c k in ih r e r L e i t f ä h i g k e i t b e e in f lu ß t w ir d . H ie r w ü r d e n w i r v o n d e n s e le k ­ t i v e n S tö r u n g s e ig e n s c h a f te n d e s zu t ie f a b g e s t im m ­ t e n M e m b r a n e m p fä n g e r s fr e i b le ib e n — w ir w ä r e n a b e r u n s ic h e r , o b n ic h t e in G a n g d e r E m p f i n d ­ lic h k e it m it d e r F r e q u e n z d e r a u ffa lle n d e n S c h a ll­

s c h w in g u n g b e s te h e n b le ib t , ü b e r d ie s w ä r e n d ie e r h a lt e n e n W e c h s e ls tr ö m e so s c h w a c h , d a ß w ir sie e r s t n a c h r e ic h lic h e r N ie d e r fr e q u e n z v e r s t ä r k u n g a u fz e ic h n e n k ö n n te n — , h ie r b e i sin d K u r v e n v e r ­ z e r r u n g e n u n v e r m e id lic h . E in e M e t h o d e , w e lc h e o b j e k t i v e in w a n d fr e ie R e s u lt a t e e r z ie le n w ill, d a r f so lc h e n E in w ä n d e n n i c h t a u s g e s e t z t se in , sie m u ß in a lle n P u n k t e n e in g e h e n d e r K r i t i k z u g ä n g lic h sein .

I c h h a b e zu m e in e n U n t e r s u c h u n g e n e in K o n ­ d e n s a t o r m ik r o p h o n n a c h H . Ri e g g e r v e r w e n d e t , d e s se n K la n g r e in h e it b e i s u b j e k t i v e r P r ü f u n g v o r z ü g lic h e R e s u lt a t e e r g a b . D a s G r u n d p r in z ip d ie s e s S c h a lle m p f ä n g e r s i s t f o lg e n d e s :

Schlitze 0,3mm in 1mm Abstand

H in t e r e in e r g e s c h lit z t e n M e t a llp l a t t e P b e f in d e t s ic h in u n g e fä h r 1/w m m A b s t a n d e in e A lu m in iu m ­ fo lie A v o n e t w a 0 ,5 fx S t ä r k e , w e lc h e z w is c h e n z w e i S e id e n m e m b r a n e n g e h a lt e n is t, d ic h t h i n t e r d e r M e m b r a n is t d e r E m p fä n g e r d u r c h e in e R ü c k ­ w a n d a b g e s c h lo s s e n . T r i f f t d u r c h P S c h a ll a u f A , so w ir d d ie s e r d ie M e m b r a n z u S c h w in g u n g e n e r ­ re g e n . D ie M a s se M d e s g e s a m t e n s c h w in g e n d e n S y s t e m s (S e id e u n d M e ta llfo lie ) b e t r ä g t n u r c a . 0 ,1 g , w ä h r e n d d ie a u f d a s S y s t e m w ir k e n d e n D ir e k t io n s k r ä f t e se h r g r o ß s in d . D ie s e K r ä f t e lie g e n in d e m z w is c h e n F o lie u n d R ü c k w a n d e in g e s c h lo s s e n e n L u f t p o ls t e r , ih r e G r ö ß e l ä ß t s ic h l e ic h t r e c h n e r is c h e r fa s s e n . D i r e k t i o n s k r a f t u n d M a s se b e s t im m e n d ie E ig e n s c h w in g u n g : sie l i e g t f ü r d a s b e s c h r ie b e n e S y s t e m b e i e t w a 6000 S c h w in g u n g e n p r o S e k u n d e , a ls o o b e r h a lb d e s S p r a c h g e b ie t e s ; sie is t ü b e r d ie s s t a r k g e d ä m p ft . B e n u t z t m a n n u n P a ls d ie e in e B e le g u n g e in e s e le k t r is c h e n K o n d e n s a t o r s u n d A a ls d ie a n d e r e , so w ir d b e im A u f t r e f f e n v o n S c h a ll d ie G r ö ß e d e r K a p a z i t ä t d ie s e s K o n d e n s a t o r s e n t s p r e c h e n d d e n a u f t r e f fe n d e n S c h a llw e lle n m o d u lie r t, b e im A n ­ n ä h e r n d e r M e m b r a n a n d ie P l a t t e wTä c h s t d ie

F ig . 1. K o n d en satorm ik ro p h on n ach H . Ri e g g e r.

F ig . 2.

D a s K o n d en sa to rm ik ro p h o n im Sch w in gun gskreis.

K a p a z i t ä t , b e im H in ü b e r g e h e n d e r M e m b r a n a u f d ie e n t g e g e n g e s e t z t e S e it e s i n k t sie. M a n s c h a lt e t n u n d a s K o n d e n s a t o r m ik r o p h o n a l s K a p a z i t ä t in e in e n e le k t r is c h e n S c h w in g u n g s k r e is £ ( F ig . 2), w e lc h e r v o n e in e r in d e r S k iz z e n ic h t g e ­ z e ic h n e t e n E le k t r o n e n r ö h r e in b e k a n n t e r W e is e in s e in e r E ig e n s c h w in g u n g e r r e g t w ir d . B e k a n n t ­ lic h i s t d ie L ä n g e d e r E ig e n w e lle d ie s e s K r e is e s d e f in ie r t a ls XR = 2 n ]/L • C , w o b e i L d ie S e lb s t ­ i n d u k t io n u n d C d ie K a p a z i t ä t d e s K r e is e s is t . M o d u lie r t m a n — w ie o b e n b e s c h r ie b e n — C d u r c h d ie a k u s t is c h e n W e lle n u m d e n B e t r a g A C s i n ß t,

. ü

w o b e i = N d ie S p r a c h f r e q u e n z se in so ll, s o w ir d e n t s p r e c h e n d d e r o b ig e n G le ic h u n g d ie W e lle n ­ lä n g e /. s ic h u m e in e n k le in e n B e t r a g A k n a c h d e r B e z ie h u n g A = /.Ä + Ax s i n ß i ä n d e r n .

D ie a k u s t is c h e n W e lle n s in d a ls o in Ä n d e r u n g e n d e r W e lle n lä n g e d e s e le k t r is c h e n S c h w in g u n g s ­ k r e is e s u m g e s e t z t . D ie A u f g a b e i s t n u n , d ie s e W e lle n ä n d e r u n g e n n a c h z u w Te ise n u n d ih r e — d e m u r s p r ü n g lic h e n K l a n g b i l d e n t s p r e c h e n d e — K u r v e n ­ f o r m a u f z u z e ic h n e n . D ie s g e s c h ie h t m it d e r M e t h o d e d e r h a lb e n R e s o n a n z k u r v e ( F ig . 3).

M a n s t im m t e in e n z w e it e n e le k t r is c h e n S c h w in ­ g u n g s k r e is R m it t e ls e in e s D r e h k o n d e n s a t o r s so a b , d a ß m a n s ic h im R u h e z u s t a n d a u f d e r h a lb e n H ö h e d e r R e s o n a n z k u r v e b e f in d e t . T r i f f t n u n S c h a ll a u f d a s K o n d e n s a t o r m ik r o p h o n in S , s o

Tr e n d e l e n b u r g: Z u r P h y s ik der K lä n g e . 663

ä n d e r t s ic h d u r c h d e n b e s c h r ie b e n e n V o r g a n g d ie e le k t r is c h e W e lle n lä n g e l R u m e n t s p r e c h e n d d ie s e n Ä n d e r u n g e n w ir d d e r S t r o m J R im R e s o n a n z ­ k r e is R u m d ie G r ö ß e A J s c h w a n k e n , n a c h G le ic h ­ r ic h t u n g d ie s e s h o c h f r e q u e n t e n S tr o m e s e r h ä lt m a n e in e n W e c h s e ls t r o m , d e r in s e in e r K u r v e g e n a u d e n B e w e g u n g e n d e r M e m b r a n f o l g t u n d d a m i t d e m K la n g b i ld e n t s p r ic h t , d a s S tr o m b ild d ie s e s S tr o m e s w ir d o s z illo g r a p h is c h r e g is t r ie r t .

D e r h ie r g e s c h ild e r t e V o r g a n g lie g t d e m v o n m ir b e n u t z t e n V e r f a h r e n z u g r u n d e , d ie E i n z e l ­ h e it e n d e r D u r c h fü h r u n g s in d e in e F r a g e d e r V e r ­ s t ä r k e r t e c h n ik , es m u ß d ie s e r h a lb a u f d ie O r ig in a l­

a r b e i t 1) v e r w ie s e n w e r d e n .

B e v o r w ir u n s d e r B e t r a c h t u n g d e r a u fg e n o m ­ m e n e n K la n g b ild e r z u w e n d e n , w o lle n w ir n o c h k u r z d ie G r u n d z ü g e d e r ü b e r d ie V o k a lk lä n g e a u f ­ g e s t e llt e n T h e o r ie n b e s p r e c h e n , d a n u r so e in V e r ­ s t ä n d n is d e r S t r u k t u r d e r K la n g b ild e r m ö g lic h is t.

H eft 33. 1 1 5 . 8 . 19 24 J

F ig . 3. D ie M ethode der halb en R e so n an zk u rve .

D e r A u s g a n g s p u n k t a lle r T h e o r ie n i s t d e r f o lg e n d e S a t z , w e lc h e r b e r e it s v o n He l m h o l t z

a u f g e s t e llt w u r d e u n d a llg e m e in e G ü l t i g k e i t b e ­ s i t z t : J e d e m V o k a l k l a n g e n t s p r ic h t e in e n g e r , f ü r d e n b e t r e ffe n d e n V o k a l c h a r a k t e r is t is c h e r u n d in s e in e r T o n h ö h e a b s o lu t f e s t e r T o n b e r e ic h . D e r in d ie s e n B e r e ic h fa lle n d e T e ilt o n d e r K l a n g ­ e n t w ic k lu n g c h a r a k t e r is ie r t d e n K la n g , e r b e w ir k t , d a ß d a s m e n s c h lic h e O h r d e n K l a n g a ls d e n b e ­ tr e ffe n d e n V o k a l e m p fin d e t . E r lä u t e r n w ir d ie s e n S a t z a n e in e m B e is p ie l:

W i r fo r d e r n v o n e in e m S ä n g e r d e n V o k a l A a u f d ie T o n h ö h e g (19 2 s e k - 1 ). D a s K la n g b i ld d e s v o n d e m S ä n g e r h e r v o r g e b r a c h t e n V o k a le s A w ir d d a n n d e n T o n 19 2 s e k - 1 a ls G r u n d t o n a u f ­ w e ise n , b e h e r r s c h e n d w ir d j e d o c h d e r 4. P a r t i a l ­ to n g le ic h 4 in a l 19 2 g le ic h 768 s e k - 1 a u f t r e t e n . D ie s e r w ir d d e n V o k a l zu e in e m A s t e m p e ln , d e n n d a s c h a r a k t e r is t is c h e G e b ie t d e s A l ie g t z w is c h e n c a . 650 u n d 800 S c h w in g u n g e n s e k " 1.

In ä h n lic h e r W e is e w ir d u n s d e r V o k a l E a u f d e r 3) F . Tr e n d e l e n b u r g, O b je k tiv e K la n g a u fz e ic h ­ n u n g m ittels des K o n d en satorm ik ro p h on s, W iss. V e r.

a. d. S iem en s-K on zern , I I I . B d ., 2. H eft, S. 43, B e r ­ lin : V e rla g von Ju liu s Sprin ger 1924.

T o n h ö h e g d u r c h d ie 14 . O b e r s c h w in g u n g c h a r a k ­ te r is ie r t , d a s b e t r e f fe n d e G e b ie t d e s E l i e g t n ä m ­ lic h b e i 2500 s e k - 1 . W ü r d e n w ir m it d e m G r u n d ­ to n h ö h e r r ü c k e n , z. B . v o n d e m S ä n g e r e in g ' fo rd e r n (384 s e k - 1), so w ü r d e w ie d e r d e r G r u n d t o n d e s K la n g b ild e s d e r g e fo r d e r t e n m u s ik a lis c h e n T o n h ö h e e n ts p r e c h e n . I m F a l l e d e s V o k a ls A w ü r d e je d o c h n ic h t d e r 4 ., s o n d e rn d e r 2. P a r t i a l ­ to n ü b e r w ie g e n d v e r t r e t e n se in , im F a ll e d e s E w ü r d e d e r 7. u n d n ic h t d e r 14 . v e r s t ä r k t e rs c h e in e n , d e n n so i s t d ie a b s o lu t e T o n h ö h e d e s c h a r a k t e r i­

s t is c h e n T o n e s g e w a h r t. I n ä h n lic h e r W e is e b e ­ s te h e n f ü r a lle V o k a lk lä n g e c h a r a k t e r is t is c h e G e ­ b ie t e ; ic h w e r d e d ie s s p ä t e r in e in e r Z u s a m m e n ­ s t e llu n g z e ig e n .

W ie i s t n u n d ie L e h r e v o n d e r a b s o lu t e n T o n ­ h ö h e d e r V o k a lk lä n g e zu e r k lä r e n ?

D e r G r u n d f ü r d ie s e E ig e n s c h a f t d e r S p r a c h - k lä n g e li e g t in d e r p h y s ik a lis c h e n W e c h s e lw ir k u n g z w is c h e n K e h lk o p f- u n d M u n d h ö h le , e s g i b t z w e i A n s c h a u u n g e n , d ie s e V o r g ä n g e zu d e u te n . D ie e r s te v o n He l m h o l t z a u f g e s t e llt e T h e o r ie l a u t e t : D a s S t im m b a n d e r z e u g t e in e n K la n g , d e s se n G r u n d ­ to n d ie m u s ik a lis c h d e fin ie r t e T o n h ö h e is t . D ie s e r K l a n g i s t re ic h a n O b e r t ö n e n ; d ie d e m K e h lk o p f v o r g e la g e r t e M u n d h ö h le g r e if t d ie je n ig e n O b e r ­ t ö n e v e r s t ä r k t h e r a u s , w e lc h e ih r e r E ig e n r e s o n a n z a m n ä c h s t e n lie g e n , u n d g i b t sie b e s o n d e rs k r ä f t i g a n d ie U m g e b u n g a b . F ü r je d e n V o k a l b ild e t m a n e in e b e s t im m t e M u n d s t e llu n g u n d d a h e r e in e g e n a u d e fin ie r t e R e s o n a n z la g e d e r M u n d h ö h le , d e r d ie s e r M u n d r e s o n a n z e n t s p r e c h e n d e T e ilt o n b e r e ic h c h a r a k t e r is ie r t d a n n d e n V o k a l.

D ie a n d e r e A n s c h a u u n g s t a m m t v o n He r­ m a n n. E r n im m t a n , d a ß im T e m p o d e s g e s u n ­ g e n e n T o n e s , d e s K e h lt o n e s , e in z e ln e L u f t s t ö ß e a u f d ie M u n d h ö h le t r e ffe n u n d d ie s e z u E ig e n ­ s c h w in g u n g e n a n r e g e n . D a s K la n g b i ld w ü r d e a ls o e in z e ln e W e lle n z ü g e a u fw e is e n , w e lc h e in d e r P e r io d e d e s g e s u n g e n e n T o n e s fo lg e n u n d in d e r E ig e n p e r io d e d e r M u n d h ö h le a b k lin g e n . D e n E ig e n t o n d e r M u n d h ö h le n e n n t He r m a n n d e n F o r m a n t e n . W i r w o lle n d ie s e n A u s d r u c k a ll­

g e m e in f ü r d a s c h a r a k t e r is t is c h e G e b ie t e in e s V o k a le s g e b r a u c h e n .

N u n e r g a b e n s ä m t lic h e b is h e r a u f g e n o m m e n e n K la n g b ild e r d e r V o k a le d ie g e n a u e P e r i o d i z i t ä t d e r K u r v e n in d e r P e r io d e d e s G r u n d to n e s . D ie v o n m ir a u fg e n o m m e n e n K la n g b ild e r b e s t ä t ig e n d ie s a u fs n e u e , e in e P e r io d e is t d e r a n d e r e n s e lb s t in ih r e r fe in s t e n S t r u k t u r v ö lli g id e n tis c h . W o llt e n w ir d ie s im S in n e He r m a n n s e r k lä r e n , so m ü ss e n w ir zu d e r A n n a h m e d e r S t o ß e r r e g u n g n o c h d ie A n n a h m e h in z u n e h m e n , d a ß a lle S t o ß im p u ls e id e n t is c h g le ic h s in d u n d ü b e r d ie s g e n a u p e r io d is c h w ie d e r k e h r e n . D ie s w ü r d e a b e r g e r a d e b e d e u te n , d a ß d ie S t ö ß e a ls e in e F o u r ie r - R e ih e s t r e n g d a r ­ s t e llb a r sin d . F ü r d ie s e F o u r ie r - E n t w ic k lu n g k ö n n ­ t e n w ir a ls d a n n n a c h d e r H e lm h o ltz s c h e n L e h r e v e r fa h r e n , w ir k ö n n te n d ie D iff e r e n t ia lg le ic h u n g d e r e r z w u n g e n e n S c h w in g u n g f ü r d ie M u n d h ö h le a ls R e s o n a n z s y s t e m a n s e tz e n u n d so d a s K la n g -

664 ^Tr e n d e l e n b u r g: Z u r P h y s ik der K lä n g e . [ Die N atur­

wissenschaften b ild d e s a u s d e r M u n d h ö h le t r e t e n d e n K la n g e s

b e r e c h n e n .

M a n k a n n d a h e r s a g e n : D ie H e lm h o ltz s c h e A n s c h a u u n g i s t r ic h t ig u n d a llg e m e in g ü lt ig . He r m a n n m a c h t f ü r b e s tim m t e F ä l l e a u ß e r d e m d ie A n n a h m e , d a ß d e r K e h l k o p f k l a n g e in e n im p u ls ­ ä h n lic h e n C h a r a k t e r a u f w e is t , e r i s t h ie r d u r c h im s t a n d e , b e s o n d e r e E ig e n t ü m lic h k e it e n d e r K l a n g ­ b ild e r , w ie sie z. B . b e im A a u f t r e t e n — a b ­ k lin g e n d e W e lle n z ü g e — , zu d e u t e n . A u s d e m e b e n G e s a g te n f o l g t n o t w e n d ig e r w e is e : U n h a r ­ m o n is c h e T e ilt ö n e k ö n n e n in k e in e m F a l l v o r ­ h a n d e n se in , d ie e r w ä h n t e n a b k lin g e n d e n W e lle n ­ z ü g e s in d in W i r k l i c h k e i t n u r d a s A b k lin g e n d e r in d e m u r s p r ü n g lic h e n K e h l k o p f k l a n g b e r e it s e n t h a lt e n e n , d e m E ig e n t o n d e r M u n d h ö h le a m n ä c h s t e n lie g e n d e n u n d d a h e r b e s o n d e r s v e r s t ä r k ­ t e n T e ilt ö n e .

E i n G e g e n s a t z z w is c h e n d e r T h e o r ie v o n He l m h o l t z u n d d e r v o n He r m a n n k ö n n t e n u r d a n n b e s te h e n , w e n n d ie e in z e ln e n I m p u ls e n ic h t s t r e n g p e r io d is c h id e n t is c h w ä r e n , d ie s e s is t a b e r, w ie b e t o n t , w e g e n d e r R e g e lm ä ß ig k e it a lle r V o k a l ­ k u r v e n a u s g e s c h lo s s e n .

Z u b e id e n A n s c h a u u n g e n b l e i b t a b e r zu b e ­ m e r k e n , d a ß d ie p h y s ik a lis c h e n V o r g ä n g e d e r K la n g e r z e u g u n g in W i r k l i c h k e i t n o c h k o m p li­

z ie r t e r se in m ü s s e n . D ie e r z w u n g e n e S c h w in g u n g e in e s e in fa c h e n S y s t e m s w ir d z u r D e u t u n g n ic h t a u s r e ic h e n , m a n m u ß a n n e h m e n , d a ß d ie V o k a l e S c h w in g u n g e n m e h r e r e r e n g g e k o p p e lte r S y s t e m e ( K e h lk o p f , R a c h e n , M u n d h ö h le ) sin d .

W i r w o lle n u n s j e t z t e in e n Ü b e r b lic k ü b e r d ie L a g e d e r F o r m a n t e n d e r H a u p t v o k a l e d e r m e n s c h ­ lic h e n S t im m e v e r s c h a ff e n . I c h w e r d e e in B i l d b r in g e n , w e lc h e s s ic h im w e s e n t lic h e n a n e in e D a r s t e llu n g b e i St u m p f a n le h n t , ic h m ö c h t e a lle r ­ d in g s d ie K l ä n g e d u r c h w e g a u f d ie s e k u n d lic h e S c h w in g u n g s z a h l, w e lc h e f ü r e in e p h y s ik a lis c h e B e t r a c h t u n g a lle in m a ß g e b e n d is t , u n d n i c h t a u f d ie m u s ik a lis c h e T o n h ö h e b e z ie h e n .

D ie B e t r a c h t u n g d e r F o r m a n t e n t a b e lle le h r t f o lg e n d e s :

D e r c h a r a k t e r is t is c h e T o n b e r e ic h d e r d u m p fe n V o k a l e U u n d O l i e g t a m tie f s t e n , e r k a n n a u c h n o c h u n t e r d ie G r e n z e v o n c a . 400 s e k “ 1 n a c h u n t e n v e r s c h o b e n se in , d ie s d r ü c k e n d ie P f e ile a u s . S o w ir d z. B . e in r e in e r S in u s t o n , d e s se n F r e q u e n z u n t e r h a lb 400 a b e r n o c h in n e r h a lb d e s a k u s t is c h e n B e r e ic h e s lie g t , a ls d u m p fe s U e m p fu n d e n . 0 u n d U s in d se h r ä h n lic h , im a llg e m e in e n p f le g t d a s U m i t e in e m T e ilt o n in G e g e n d 800 e in w e n ig a u f ­ g e h e llt zu se in , w ä h r e n d d a s 0 n o c h w e it e r h i n a u f ­ r e i c h t u n d s o g a r n o c h b e i 3000 e in e n b e t r ä c h t ­ lic h e n Z u s a t z e n t h ä lt . I c h w e r d e h ie r a u f n o c h zu s p r e c h e n k o m m e n .

D e r F o r m a n t e n b e r e ic h d e s A l i e g t z w is c h e n e t w a 6 50 u n d 800 s e k “ 1 u n d t r i t t b e s o n d e r s s t a r k h e r v o r , d ie in d ie s e n B e r e ic h fa lle n d e n T e ilt ö n e t r e t e n m e is t m it e in e r A m p lit u d e a u f, w e lc h e g r ö ß e r i s t a ls d ie d e s G r u n d to n e s .

D ie V o k a l e E u n d I w e is e n je z w e i F o r m a n t e n ­

b e r e ic h e a u f, d e r n ie d e r e l ie g t f ü r b e id e e b e n fa lls b e i 400 s e k " 1, d e r h ö h e re , b e s o n d e r s c h a r a k t e ­ r is t is c h e , b e f in d e t s ic h f ü r E in G e g e n d 2500 s e k - \ w ä h r e n d e r f ü r d a s I in G e g e n d 3000 b is 3500 lie g t .

D ie F o r m a n t e n g e b ie t e s in d in d iv id u e ll e in w e n ig v e r s c h ie d e n , f ü r d a s E in z e lin d iv id u u m a b e r f e s t u n d c h a r a k t e r is t is c h .

D ie R i c h t i g k e i t d e r e b e n b e s c h r ie b e n e n F o r ­ m a n te n la g e i s t d u r c h z a h lr e ic h e e x p e r im e n t e lle U n t e r s u c h u n g e n b e s t ä t i g t . A u c h m e in e A u f ­ n a h m e n g lie d e r n s ic h in d ie s e n R a h m e n e in . D a r ­ ü b e r h in a u s f a n d ic h h o h e c h a r a k t e r is t is c h e T e i l ­ t ö n e fü r A , O u n d U in G e g e n d 2800 b is 3200 s e k - 1,

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ic h h a b e d ie s e B e r e ic h e in d e r Z e ic h n u n g d u r c h S c h r a f f u r g e k e n n z e ic h n e t . D ie s e r h o h e T o n b e r e ic h is t , w ie ic h z e ig e n w e r d e , f ü r d ie in d iv id u e lle K la n g f a r b e a u s s c h la g g e b e n d . E i n k r ä ft ig e s A u f ­ t r e t e n d ie s e r h o h e n T e ilt ö n e b e w ir k t , d a ß d e r K l a n g e in e n h e lle n m e t a llis c h e n C h a r a k t e r a n ­ n im m t , i s t h in g e g e n d ie i n d iv id u e ll c h a r a k t e r i­

s t is c h e F e i n s t r u k t u r n u r m it g e r in g e r A m p lit u d e v e r t r e t e n , so b e s i t z t d e r K l a n g e in e n w e ic h e n C h a r a k t e r . D ie h o h e n T e ilt ö n e s in d fü r A im a llg e m e in e n b e s o n d e r s a u s g e s p r o c h e n , w e n ig e r f ü r O u n d a m g e r in g s te n fü r U . I c h h a b e d ie s in d e m B i ld d u r c h d ie v e r s c h ie d e n e B r e it e d e r R e c h t ­ e c k e zu k e n n z e ic h n e n v e r s u c h t .

W i r wollen n u n d ie d u r c h das Kondensator­

m ik r o p h o n a u f g e d e c k t e F e i n s t r u k t u r d e r K lä n g e im e in z e ln e n a n H a n d e in ig e r v o n mir a u fg e n o m ­ m e n e n K la n g b i ld e r b e s p r e c h e n .

E s so ll h ie r n o c h a u s d r ü c k lic h a u f d e n E in f lu ß d e r g e s a n g lic h e n S c h u lu n g a u f d ie p h y s ik a lis c h e n E ig e n s c h a f t e n d e r K l ä n g e h in g e w ie s e n w e rd e n . D ie s e V e r ä n d e r u n g e n z e ig e n a m b e s te n d ie ^ .- K la n g ­ b ild e r . W u r d e v o n d e r V e r s u c h s p e r s o n e in A m it

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F ig . 5 A 191 4 ^{764 16} 3056 M ännerstim m e, V o k a lc h a ra k te r sta r k b e to n t, m etallisch er K la n g F ig. 6 A 192 4 ⁷⁸⁶ 15 2880 die gleiche Stim m e entsp rechen d ih rer gesan glichen Sch ulu ng

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F ig .11 1 351 9 3159 F rauen stim m e

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F i g - i3 ^U 291 — — — — M ännerstim m e, sehr d um pfer, K la n g ch a ra k te r

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F ig. 7. V o k a l A , M än n erstim m e G ru n d ton 192 s e k - 1 . F ig. 8. V o k a l A , F rau en stim m e. G ru n d ton 441 s e k - 1 . V o k a lc h a ra k te r sta rk b eto n t.

F ig . 9. V o k a l A , F rauen stim m e. G run d ton 398 s e k - 1 , entsp rechen d der gesan glichen Sch ulu ng.

F ig. 10. V o k a l E , M ännerstim m e. G run d ton 201 s e k - 1 .

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6 6 6 Tr e n d e l e n b u r g: Z u r P h y s ik d er K lä n g e . T Die Natur - l Wissenschaften b e s o n d e r s b e t o n t e m V o k a l c h a r a k t e r g e fo r d e r t , so

t r a t s t e t s d e r ^4- F o r m a n t is o lie r t a u f, w ä h r e n d in d e m d e r g e s a n g lic h e n S c h u lu n g e n t s p r e c h e n d e n K la n g b i ld d ie b e n a c h b a r te n T e ilt ö n e m it n a h e z u g le ic h e r A m p lit u d e v e r t r e t e n s in d , d ie s v e r le ih t d e m K l a n g e in e n w e ic h e n u n d v o lle n C h a r a k t e r .

D ie d u r c h m e in e K la n g a u fn a h m e n o b j e k t i v a u f g e d e c k t e F e i n s t r u k t u r d e r K l ä n g e w u r d e v o n St u m p f a n e in e m V o k a l, d e m A , b e r e it s s u b j e k t i v f e s t g e s t e llt . E r f a n d e b e n fa lls , d a ß g e r a d e d e r B e r e ic h u m 3000 s e k n o c h i n d iv id u e ll w ic h t ig e T e ilt ö n e e n t h ie lt . D ie e n t s c h e id e n d e B e d e u t u n g d ie s e r T o n b e r e ic h e f ü r d ie p e r s ö n lic h e K l a n g ­ f a r b e l ä ß t s ic h m it d e m K o n d e n s a t o r m ik r o p h o n e b e n fa lls le ic h t n a c h w e is e n . S t i m m t m a n n ä m ­ lic h d e n S c h a lle m p f ä n g e r d u r c h V e r g r ö ß e r u n g d e s L u f t p o ls t e r s z w is c h e n F o lie u n d R ü c k w a n d so a b , d a ß se in e E ig e n s c h w in g u n g e t w a in G e g e n d 2000 s e k - 1 lie g t , so w e r d e n d ie h o h e n T e ilt ö n e n u r n o c h m i t v e r s c h w in d e n d k le in e r A m p lit u d e w ie d e r ­ g e g e b e n , d ie S p r a c h e n im m t e in e n d u m p fe n C h a r a k t e r a n , sie is t z w a r n o c h v e r s t ä n d lic h , d o c h i s t d ie p e r s ö n lic h e F ä r b u n g v e r lo r e n .

W i r h a t t e n in d e m b is h e r G e s a g t e n d ie G e s e t z e d e r K l a n g b i ld u n g b e s p r o c h e n , w ir h a t t e n a u f e x p e r im e n t e lle m W e g e e in ig e c h a r a k t e r is t is c h e B ild e r d e r H a u p t v o k a l e a u fg e z e ic h n e t , w ir h a t t e n g e se h e n , in w e lc h e n p h y s ik a lis c h e n E ig e n t ü m lic h ­ k e it e n d ie p e r s ö n lic h e K la n g f a r b e d ie s e r K lä n g e b e s ta n d . I c h h a t t e o b e n b e t o n t , d a ß d ie s e re in w is s e n s c h a ft lic h e n F e s t s t e llu n g e n e in e m e r h e b lic h e n te c h n is c h e n I n t e r e s s e b e g e g n e n , w ir w o lle n d ie s e n te c h n is c h e n G e s ic h t s p u n k t j e t z t k u r z b e s p r e c h e n .

D ie t e c h n is c h e n P r o b le m e , f ü r w e lc h e d ie K la n g fo r s c h u n g e in e g r u n d le g e n d e R o lle s p ie lt , s in d d ie F e r n ü b e r t r a g u n g d e r n a t ü r lic h e n K lä n g e u n d d ie K la n g a u fz e ic h n u n g z w e c k s s p ä t e r e r R e p r o ­ d u k t io n . D ie so ü b e r t r a g e n e n o d e r a u f g e z e ic h ­ n e t e n n a t ü r lic h e n K l ä n g e w e r d e n d e m O h r a ls k ü n s t lic h e , d u r c h e in e n W ie d e r g a b e a p p a r a t e r ­ z e u g t e K l ä n g e z u g e le it e t .

F ig . 15. D as W eb er-F ech n ersch e G esetz.

W i r w o lle n j e t z t d a s G e s e t z b e t r a c h t e n , w e lc h e s d ie U m s e t z u n g d e r a k u s tis c h e n W e lle n in s u b ­ j e k t i v e E m p fin d u n g d u r c h d a s G e h ö r s o r g a n b e ­ h e r r s c h t . D ie s G e s e t z i s t d a s W e b e r - F e c h n e r s c h e G e s e t z , ic h h a b e e s in F i g . 15 g r a p h is c h d a r g e s t e llt , es l a u t e t in W o r t e n : D ie S t ä r k e d e r s u b je k t iv e n

E m p fin d u n g ( E subj.) i s t p r o p o r t io n a l d e m L o g a ­ r it h m u s d e r a u ffa lle n d e n S c h a llin t e n s it ä t ( I phys.)- L a s s e n w ir a ls o d ie S c h a llin t e n s it ä t v o n se h r k le in e n W e r te n a u s a llm ä h lic h a n s te ig e n , so e m p f in d e t u n s e r O h r z u n ä c h s t n ic h t s , b is d e r S c h w e lle n w e r t d e s O h r e s e r r e ic h t w ir d (/ — 1, lo g 1 — E — o ) ; h ie r s e t z t d ie E m p fin d u n g p l ö t z ­ lic h e in u n d s t e i g t z u n ä c h s t m it w a c h s e n d e m R e iz s t a r k a n , u m d a n n e n ts p r e c h e n d d e m V e r la u f d e r lo g a r it h m is c h e n F u n k t io n b e i w e it e r e r S t e ig e r u n g d e r S c h a llin t e n s it ä t n u r n o c h la n g s a m z u z u n e h m e n .

v ' 4 « v W - »

F ig. 16. a K o n d en sato rm ik ro p h o n , & Po stm ikro p ho n .

W ir h a b e n n u n d ie M ö g lic h k e it , e in e n a h e ­ lie g e n d e u n d te c h n is c h w ic h t ig e F r a g e zu k lä r e n : W ie i s t es ü b e r h a u p t m ö g lic h , d a ß d a s O h r z w e i ä u ß e r lic h so v e r s c h ie d e n e K la n g k u r v e n , w ie sie z. B . d u r c h d a s K o n d e n s a t o r m ik r o p h o n u n d d u r c h d a s K o h le k ö r n e r m ik r o p h o n a u fg e n o m m e n w e r d e n , s u b j e k t i v a ls d e n g le ic h e n V o k a l k l a n g e m p fin d e t .

U m zu z e ig e n , w ie v e r s c h ie d e n d e r a r t ig e K l a n g ­ b ild e r a u s fa lle n k ö n n e n , h a b e ic h a u f O s z illo - g r a m m (F ig . 16 ) g le ic h z e it ig d e n V o k a l A e in e r M ä n n e r s t im m e m it d e m K o n d e n s a t o r m ik r o p h o n u n d m it e in e m P o s t m ik r o p h o n a u fg e n o m m e n .

D ie F e i n s t r u k t u r i s t b e i d e m P o s t m ik r o p h o n f a s t v ö llig v e r s c h w u n d e n , w ä h r e n d T e ilt ö n e im B e r e ic h v o n 700 b is 1200 s e k _1 s t a r k v e r t r e t e n s in d . D ie T a t s a c h e , d a ß d a s O h r a u c h d ie s e n K l a n g a ls A e m p fin d e t , l ie g t e r s te n s in d e r R i c h t i g k e i t d e r F o r m a n t e n t h e o r ie : d e r F o r m a n t d e s A is t a u c h in d e m K la n g b ild d e s P o s t m ik r o p h o n s s t a r k v e r t r e t e n u n d s t e m p e lt d ie s e n K l a n g zu e in e m A , u n d z w e it e n s in d e r R i c h t i g k e i t d e s W e b e r - F e c h - n e r s c h e n G e s e t z e s : v e r h ä lt n is m ä ß ig g r o ß e A m p li ­ t u d e n u n t e r s c h ie d e k o m m e n d e m O h r s u b j e k t i v k a u m z u r E m p fin d u n g . D ie h ö h e re n T e ilt ö n e s in d in d e m K la n g b i ld d e s P o s t m ik r o p h o n s n u r e b e n a n g e d e u t e t , sie w e r d e n b e i d e r W ie d e r g a b e te ilw e is e u n t e r d e n S c h w e lle n w e r t d e s O h re s s in k e n , d a d u r c h f ä l l t d e r b e t r e ffe n d e T e ilt o n s u b j e k t i v g a n z a u s , d ie F e in h e it d e r p e rs ö n lic h e n K la n g f a r b e w e r d e n n ic h t w ie d e r g e g e b s n .

D a s e b e n G e s a g t e b e w e is t a u c h d ie W ic h t ig k e it s c h w e lle n w e r t fr e ie r E m p fä n g e r u n d s o lc h e r E m p ­ fä n g e r , d e re n A m p lit u d e n d e r e rre g e n d e n K r a f t n a c h e in e m lin e a r e n G e s e t z fo lg e n .

D ie e r s te F o r d e r u n g i s t n a c h d e m G e s a g te n o h n e w e ite r e s k l a r : w ie w e n ig sie fü r v ie le M ik r o ­ p h o n e e r f ü llt is t, z e ig t d ie fo lg e n d e , le ic h t zu g e ­ w in n e n d e B e o b a c h t u n g :

^Heft 33. j H a u p tv e rsa m m lu n g d. D eu tsch en B u n sen -G esellsch aft f. a n g ew a n d te p h y sik al. Chem ie. 6 6 7

D a s A u fn a h m e m ik r o p h o n b e f in d e t s ic h in e in e m Z im m e r, in w e lc h e m e n t fe r n t v o m M ik r o ­ p h o n g e s p r o c h e n w ir d .

M a n h ö r t d a n n im M ik r o p h o n z w a r d e u t lic h , d a ß g e s p r o c h e n w ir d , i s t a b e r n ic h t im s ta n d e , a u c h n u r e in W o r t zu v e r s t e h e n : z a h lr e ic h e F o r m a n t e n s in d in ih r e r A m p lit u d e zu k le in , u m d e n S c h w e l­

le n w e r t d e s M ik r o p h o n e s zu e rre ic h e n , sie fa lle n i n d e m s e k u n d ä r e n K la n g b i ld d e s T e le p h o n e s g a n z a u s : d ie S p r a c h e w ir d u n v e r s t ä n d lic h .

D ie W i c h t i g k e i t lin e a r e r E m p fä n g e r li e g t in d e m U m s ta n d , d a ß z. B . b e i q u a d r a t is c h e r E m p ­ f a n g s c h a r a k t e r is t ik d e s A u f n a h m e a p p a r a t e s n e b e n d e n u r s p r ü n g lic h e n T e ilt ö n e n s o lc h e v o n d o p p e lt e r F r e q u e n z a u f tr e te n , so d a ß F o r m a n t e n v o r g e t ä u s c h t w e r d e n k ö n n e n , d ie g a r n ic h t v o r h a n d e n sin d , u n d m it h in e in fr e m d e r K l a n g c h a r a k t e r e n t s t e h t .

D ie T e c h n ik s t e llt f ü r d ie N a c h r ic h t e n ü b e r ­ m it t e lu n g im a llg e m e in e n d ie F o r d e r u n g , d a ß d e r F r e q u e n z b e r e ic h z w is c h e n e t w a 700 u n d 2 10 0 s e k - 1 e in ig e r m a ß e n g le ic h m ä ß ig w ie d e r g e g e b e n w ir d , o b g le ic h b e k a n n t is t , d a ß w ic h t ig e

F o r m a n t e n b e r e ic h e a u ß e r h a lb d ie s e r S c h w in g u n g s z a h le n lie g e n . I n d ie sen F ä ll e n h i lf t u n s Ü b u n g , P h a n ta s ie u n d K o m b in a t io n s g a b e z u m V e r ­ s t ä n d n is e in e r in ih r e m K l a n g d e r a r t e in g e e n g te n S p r a c h e .

D ie la n g jä h r ig e E r fa h r u n g im G e ­ b r a u c h d e s F e r n s p r e c h e r s l ä ß t u n s

d ie s e K la n g e in e n g u n g ü b e rh ö r e n . W ie w e i t ­ g e h e n d d ie E n t s t e llu n g e n s in d , m ö g e n z w e i k u r z e B e m e r k u n g e n z e ig e n . Z u n ä c h s t m ö c h t e ic h a u f d ie g r o ß e S c h w ie r ig k e it fr e m d s p r a c h ­ lic h e n F e r n s p r e c h v e r k e h r s h in w e is e n : s e lb s t b e i a u s g e z e ic h n e t e r B e h e r r s c h u n g d e r fr e m d e n S p r a c h e is t u n s ih r e in g e e n g te r T e le p h o n k la n g n i c h t g e w o h n t, w ir h a b e n k e in e K o m b in a t io n s - m ö g lic h k e it e n u n d v e r s t e h e n d a h e r a u ß e r o r d e n t ­ lic h sc h w e r .

D ie z w e it e B e m e r k u n g is t d ie fo lg e n d e : W ir w e r d e n a n g e r u fe n u n d v e r s t e h e n d e n N a m e n d e s

A n r u fe n d e n n ic h t , w ir s te h e n d e m I n h a lt d e s G e ­ s p r ä c h e s z u n ä c h s t v e r s t ä n d n is lo s g e g e n ü b e r , b is u n s e in v e r s ta n d e n e s , fü r d e n Z u s a m m e n h a n g w ic h t ig e s W o r t z e ig t , u m w a s s ic h d a s G e s p r ä c h h a n d e lt u n d w ir n u n a u f d ie P e r s o n d e s A n r u fe n d e n s c h lie ß e n k ö n n e n . M it d ie s e m A u g e n b lic k h a b e n w ir d e n Ü b e r s e t z u n g s s c h lü s s e l T e le p h o n k la n g ­ fa r b e — p e r s ö n lic h e K la n g f a r b e g e w o n n e n , u n d w ir k ö n n e n m ü h e lo s fo lg e n .

I c h h a b e d ie G r ü n d e g e z e ig t , w e lc h e es e r ­ m ö g lic h e n , fü r d ie g e w ö h n lic h e n Z w e c k e d e r F e r n ­ m e ld e t e c h n ik m it e in e m e n g e r e n T o n b e r e ic h 'a u s­

z u k o m m e n .

F ü r e in e w ir k lic h n a t u r g e t r e u e K la n g w ie d e r ­ g a b e m ü ss e n w ir a b e r w e ite r g e h e n d e F o r d e r u n g e n a u f s t e l l e n : D ie Ü b e r t r a g u n g u n d d ie R e p r o d u k t io n m u ß so e r fo lg e n , d a ß d e r F r e q u e n z b e r e ic h z w is c h e n 50 u n d 5000 S c h w in g u n g e n p r o S e k u n d e e in ig e r ­ m a ß e n g le ic h m ä ß ig w ie d e r g e g e b e n w ir d , lie g e n j a d o c h sc h o n d ie h o h e n T e ilt ö n e d e r V o k a le b e i u n d ü b e r 3000 s e k - 1 , K o n s o n a n t e n , n a m e n t lic h

d ie Z is c h la u t e re ic h e n n o c h h ö h e r h in a u f. (V g l.

O s z illo g r a m m F ig . 17 .)

D ie m i t d e r b e s c h r ie b e n e n A n o r d n u n g d u r c h ­ g e fü h r t e n U n t e r s u c h u n g e n lie fe r t e n w e itg e h e n d e n A u f s c h lu ß ü b e r d ie S t r u k t u r d e r S p r a c h la u t e , d ie in d iv id u e lle n K la n g e ig e n t ü m lic h k e it e n k o n n te n o b j e k t i v e r f a ß t w e rd e n . E s w ir d s ic h lo h n e n , d ie U n t e r s u c h u n g e n a u c h a u f d ie K lä n g e d e r M u s ik ­ in s t r u m e n te a u s z u d e h n e n . D ie e m p ir is c h g e ­ w o n n e n e E r fa h r u n g s t e c h n ik i s t h ie r d e r a r t w e i t v o r g e s c h r it t e n , d a ß n u r e in e h o c h w e r t ig e V e r ­ s u c h s t e c h n ik fö r d e r n d e in g r e ife n k a n n .

F ig . 17. Z isch lau t Sch , sehr sch arf. M ittlere F req u en z 4500 s e k - 1 .

H auptversam m lung der D eutschen Bunsen-Gesellschaft für angewandte physikalische Chemie.

G öttin g en , das schon 25 Jahre zu v o r d ie D eu tsch e B u n sen -G esellsch aft beh erb ergt h a tte , ü b te heu er eine beson dere A n zieh u n g sk ra ft au s: v erein ig ten sich doch m ehr als 360 T eiln ehm er zu der diesjäh rigen V e rsam m ­ lu n g am 30. und 31. M ai, fa s t zu v ie l selb st fü r das A u d i­

to riu m m axim um , in dem der g rö ß te T e il der V o rträg e, und besonders fü r den H ö rsaal des P h y sik a lisch e n I n ­ s titu ts, in dem die E x p e rim e n ta lv o rtr ä g e geh alten w u rden . D em en tsp rechen d w a r a u ch d ie A n z a h l der V o rträ g e u n g ew ö h n lich g ro ß ; m ehr als 40 w u rd en in 2 A rb eitstag e n b e w ä ltig t, so d aß dem E in zeln en die R ed ezeit sehr k n ap p zugem essen u nd die D isku ssion a u fs äu ß erste b e sch rä n k t w erden m u ß te. H o ffen tlic h lä ß t sich a b er die v o n einem B eg rü ß u n g sred n er als Z u k u n ftsm ö g lich k eit a n g ed eu tete U n te rte ilu n g der G esellsch a ft verm eid en , der gerade die V e re in ig u n g der g esam ten reinen und an g ew a n d ten p h y sik alisch e n C h e­

m ie in ein A rb eitsg eb iet ih r besonderes G epräge v e r­

leih t.

D ie zusam m en fassen den V o rträ g e des ersten V o r­

m itta g s w aren u n ter L e itu n g v o n Ta m m a n n — dem k ü n ftig en V o rsitzen d en der G esellsch aft — der Chemie der hohen Tem peraturen gew id m et.

H ohe T em p eratu ren , so ho ch sie n ach dem jew eiligen S tan d e d er E rh itzu n g ste ch n ik zu erreichen w aren, h a t ja die Chem ie seit den ä ltesten Z eiten a n g ew an d t;

w issen schaftlich e B ed eu tu n g gew in n en a b er solche V e r­

suche erst dann, w en n die T em p eratu ren gem essen w erd en . D em gem äß besp rach an erster S telle He n n i n g

(von d er P h ysik a lisch -T ech n isch en R eich san stalt) das P rob lem der M essung hoher Temperaturen, der P y r o - m etrie, w o b ei er sich w egen der n ach trä g lich v erk ü rz te n R e d ezeit a u f die optischen V erfah ren besch ränken m u ß te. D iese beruhen ja a u f dem Z u sam m en han g