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Syftet med föreliggande studie var att undersöka sambandet mellan subglottalt tryck och ljudtrycksnivå, och undersöka inverkan av kön och tonhöjd. Röststyrkan är starkt beroende av subglottalt tryck och sambandet har analyserats i ett flertal studier, som alla visar på ett linjärt förhållande mellan logaritmen av subglottala trycket och ljudtrycksnivån (SPL). Schutte (1980) analyserade sambandet för 21 kvinnor och  24 män som producerade ett stort antal mätdata med olika SPL och tonhöjd. Tryck mättes med ballong i esofagus. Tanaka & Gould (1982) analyserade 4 kvinnor och 6 män på tre ljudnivåer på bekväm tonhöjd; svag, normal och stark ljudstyrka. Subglottalt tryck uppmättes med pletysmograf, med försökspersonen sittandes i lufttät box. Pressad fonation karaktäriseras av ett högt subglottalt tryck och en förhållandevis låg SPL, så sambandet mellan tryck och SPL torde påverkas av glottal adduktion och troligen också av tonhöjd. Därför borde normativa data från röstfriska personer vara av intresse. I denna studie producerade 16 kvinnor och 15 män sekvenser av stavelsen [pæ] på fyra tonhöjder, jämnt fördelade över en oktav. Regressionsanalys användes för att approximera sambandet mellan SPL och logaritmen av subglottalt tryck samt för att beräkna genomsnittlig SPL-ökning för dubblat subglottalt tryck och beräknad SPL vid 10 cm H2O. Resultatet visar som väntat ett mycket starkt samband mellan subglottalt tryck och ljudtrycksnivån, med en korrelationskoefficient på 0.835 respektive 0.826 för kvinnor respektive män. En fördubbling av subglottalt tryck gav en genomsnittlig SPL-ökning av 11,5 dB (SD 3.8) för kvinnor och 10,0 dB (SD 2,7) för män. Skillnaden mellan kvinnor och män var här signifikant, vilket ger stöd för att använda separativa normativa värden för kvinnor och män. Genomsnittlig beräknad nivå vid 10 cm H2O var 83,6 dB (SD 3,9) för kvinnor och 82,2 dB (SD 4,6) för män beräknat till 15 cm mikrofonavstånd. Sambandet mellan subglottalt tryck och SPL skiljde sig en aning beroende på tonhöjd, men skillnaden var ej signifikant. Trots de relativt höga standardavvikelserna tyder resultatet på att det vore värt att studera i vad mån avvikelser från de potentiellt normativa värdena skulle kunna vara tecken på någon slags fonatorisk dysfunktion. / The purpose of this study was to examine the relationship between subglottal pressure and sound pressure level (SPL), and to study the importance of gender and fundamental frequency in this relationship. Vocal loudness is strongly dependent on subglottal pressure. The relation between them has been analyzed in several investigations, all showing a linear relationship between the SPL and the log of the pressure. For example, Schutte (1980) analyzed the relation in 21 female and 24 male subjects who produced a great number of samples at different degrees of vocal loudness and at the subjects’ preferred pitch. Pressure was measured by means of an esophageal balloon. Tanaka and Gould (1982) analyzed 10 subjects each producing vowels at three loudness levels at comfortable pitch. Pressure data were obtained from a plethysmograph, with the subject sitting in an airtight box. Pressed phonation is characterized by a high subglottal pressure producing a comparatively low SPL, so hence the pressure – SPL relationship would be affected by glottal adduction and possibly also by F0. Therefore normative data from healthy voices should be of interest. In the present study 16 female and 15 male normal voices were asked to produce diminuendo and crescendo sequences of the syllable [pæ] at four pitches, equidistantly spaced within an octave. Trendlines were used to approximate the relation between SPL and the log of subglottal pressure. The resulting regression equations were used to calculate the average SPL increase for doubling of pressure and the SPL produced by a pressure of 10 cm H2O. The results showed an average correlation coefficient of 0.835 and 0.826 for female and male subjects. A doubled pressure produced an SPL increase of 11.5 dB (SD 3.8) and 10.0 dB (SD 2.7) for the female and the male voices. The difference between female and male voices was significant, which supports use of separate normative values for female and male voices. On average, a subglottal pressure of 10 cm H2O produced an SPL @ 0.15 m of 83.6 dB (SD 3.9) and 82.2 dB (SD 4.6) for the female and the male voices. The relationship between subglottal pressure and SPL depended somewhat on fundamental frequency, but the difference was not significant. In spite of the relatively high standard errors the results indicate that it would be worth to study in what extent differences from the potentially normative values of this study may be a sign of some sort of phonatory dysfunction.

This thesis addresses aspects of voice characteristics in operatic and musical theatre singing. The common aim of the studies was to identify respiratory, phonatory and resonatory characteristics accounting for salient voice timbre differences between singing styles. The velopharyngeal opening (VPO) was analyzed in professional operatic singers, using nasofiberscopy. Differing shapes of VPOs suggested that singers may use a VPO to fine-tune the vocal tract resonance characteristics and hence voice timbre. A listening test revealed no correlation between rated nasal quality and the presence of a VPO. The voice quality referred to as “throaty”, a term sometimes used for characterizing speech and “non-classical” vocalists, was examined with respect to subglottal pressure (Psub) and formant frequencies. Vocal tract shapes were determined by magnetic resonance imaging. The throaty versions of four vowels showed a typical narrowing of the pharynx. Throatiness was characterized by increased first formant frequency and lowering of higher formants. Also, voice source parameter analyses suggested a hyper-functional voice production. Female musical theatre singers typically use two vocal registers (chest and head). Voice source parameters, including closed-quotient, peak-to-peak pulse amplitude, maximum flow declination rate, and normalized amplitude quotient (NAQ), were analyzed at ten equally spaced subglottal pressures representing a wide range of vocal loudness. Chest register showed higher values in all glottal parameters except for NAQ. Operatic baritone singer voices were analyzed in order to explore the informative power of the amplitude quotient (AQ), and its normalized version NAQ, suggested to reflect glottal adduction. Differences in NAQ were found between fundamental frequency values while AQ was basically unaffected. Voice timbre differs between musical theatre and operatic singers. Measurements of voice source parameters as functions of subglottal pressure, covering a wide range of vocal loudness, showed that both groups varied Psub systematically. The musical theatre singers used somewhat higher pressures, produced higher sound pressure levels, and did not show the opera singers’ characteristic clustering of higher formants. Musical theatre and operatic singers show highly controlled and consistent behaviors, characteristic for each style. A common feature is the precise control of subglottal pressure, while laryngeal and vocal tract conditions differ between singing styles. In addition, opera singers tend to sing with a stronger voice source fundamental than musical theatre singers. / <p>QC 20100812</p>

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