The Effects of Frequency Range, Vowel, Dynamic Loudness Level, and Gender on Nasalance in Amateur and Classically Trained Singers

Nasalance, Nasal Airflow and Perceived Nasality in Carnatic Singers and Non-singers

This study aims to compare the nasalance and nasal airflow between professional singers trained in Carnatic classical singing and non-singers. We also aimed to correlate perceived nasality with objective measurements of nasalance and nasal airflow. A total of 40 female participants (20 to 50 years) were involved in this study. The first group comprised 15 female professional Carnatic singers with a minimum of 10 years of classical training. The second group consisted of 25 non-singer females. These participants were compared on nasalance, nasal airflow and perceived nasality across three sets of stimuli (vowels, oral non-words, and nasal non-words) and three pitch-conditions (low, mid, and high). Correlations were also made between objective measures of nasalance and nasal airflow and perceived nasality. Mixed ANOVA showed a significant (P < 0.05) interaction in nasalance between pitch conditions and groups. Group differences were also observed in the nasalance scores of vowels, oral non-words, nasal non-words. There was a significant difference (P < 0.05) in nasalance with ascending pitch in singers and non-singers. A comparison of aerodynamic analysis of vowels, oral non-words, and nasal non-words between singers and non-singers suggested that nasal airflow was higher in singers. Perceptual nasality was significantly lower (P < 0.05) in Carnatic singers than non-singers. Correlations between objective measures of nasalance and nasal airflow and perceived nasality were not observed. Despite an increased airflow, nasality was lower in trained Carnatic singers than non-singers. Current findings suggest that vocal training impacts nasalance, nasal airflow and perceived nasality.

Dynamic changes of vocal tract dimensions with sound pressure level during messa di vocea)

The messa di voce (MdV), which consists of a continuous crescendo and subsequent decrescendo on one pitch is one of the more difficult exercises of the technical repertoire of Western classical singing. With rising lung pressure, regulatory adjustments both on the level of the glottis and the vocal tract are required to keep the pitch stable. The dynamic changes of vocal tract dimensions with the bidirectional variation of sound pressure level (SPL) during MdV were analyzed by two-dimensional real-time magnetic resonance imaging (25 frames/s) and synchronous audio recordings in 12 professional singer subjects. Close associations in the respective articulatory kinetics were found between SPL and lip opening, jaw opening, pharynx width, uvula elevation, and vertical larynx position. However, changes in vocal tract dimensions during plateaus of SPL suggest that perceived loudness could have been varied beyond the dimension of SPL. Further multimodal investigation, including the analysis of sound spectra, is needed for a better understanding of the role of vocal tract resonances in the control of vocal loudness in human phonation.

The Role of Instructions in Motor Learning of Oral Versus Nasalized Speech Targets

PURPOSE

The purpose of this study was to investigate how general, implicit instructions with auditory-perceptual emphasis; specific, explicit instructions with biomechanical focus; or both affect learning of oral-nasal balance control in speech.

METHOD

Thirty healthy, vocally untrained participants were assigned to one of three instructional groups (i.e., implicit, explicit, and integrated) and learned to produce oral versus nasalized vowel-, syllable-, and phrase-level targets during once-weekly sessions over 4 weeks. Learning gains and performance variability were analyzed using nasometry.

RESULTS

We observed a significant main effect of instruction type on learning gains at phrase level (p = .016). Specifically, the integrated group (M = 59.8%) significantly outperformed the explicit group (M = 37.9%) and numerically outperformed the implicit group (M = 45.1%). For nasalized phrase targets, results revealed a significant main effect of instruction type on performance variability (p = .042), but pairwise comparisons between instruction groups were not significant.

CONCLUSIONS

The integration of implicit processes via auditory-perceptual modeling and explicit processes via relevant biomechanical directives resulted in larger motor learning gains, especially at higher levels of task complexity (i.e., phrase) compared to providing implicit or explicit instruction alone. The higher performance variability (i.e., less stable productions) that was sometimes induced by explicit instruction did not negatively impact learning when integrated with implicit instruction. Clinical implications for speech/voice therapy models are discussed.

Finite element modeling of the effects of velopharyngeal opening on vocal tract reactance in female voice

Classical singers use nasal consonants as "resonance exercises," and experimental results have shown that singers may use some velopharyngeal opening (VPO), most often in [a:] and more seldom in [i:] or [u:]. In particular, male singers have been found to increase VPO as pitch rises toward register change frequencies (passaggi). Laryngoscopic findings have shown that some VPO stabilizes vocal fold vibration; the effect is related to positive reactance. This study investigates the effects of VPO on vocal tract (VT) reactance over the range of fundamental frequencies (f₀) used in singing using a computerized tomography-based finite element model of the VT and nose of a female. According to the results, by raising the lowest VT resonances, the VPO increased the VT reactance in the frequency ranges 207-359 Hz for [i:], 265-411 Hz for [u:], and 500-611 Hz for [a:], depending on the VPO size (full or half VPO). These frequency ranges are close to the first and second passaggio of a female singer. The change may have an especially practical stabilizing effect for [a:], which is otherwise characterized by very large changes in VT reactance and negative reactance at the second passaggio.

Immediate effects of voice focus adjustments on hypernasal speakers' nasalance scores

OBJECTIVES

To explore the immediate effects of voice focus adjustments on the oral-nasal balance of hypernasal speakers, measured with nasalance scores.

METHODS

Five hypernasal speakers (2 M, 3 F) aged 5-12 (SD 2.7) learned to speak with extreme forward and backward voice focus. Speakers repeated oral, nasal, and phonetically balanced stimuli. Nasalance scores were collected with the Nasometer 6450.

RESULTS

From the average baseline of 34.27% for the oral stimulus, nasalance increased to 46.07% in forward and decreased to 30.2% in backward focus. From the average baseline of 64.53% for the nasal stimulus, nasalance decreased to 64.13% in forward and decreased to 51.73% in backward focus. From the average baseline of 51.33% for the phonetically balanced stimulus, nasalance increased to 58.87% in forward and decreased to 46.2% in backward focus.

CONCLUSIONS

Forward voice focus resulted in higher and backward voice focus resulted in lower nasalance scores during speech for a group of hypernasal speakers. However, there was an exception: One male speaker showed decreased nasalance in forward voice focus. Future research should investigate the longer-term effectiveness of the intervention.

Effects of Knowledge of Task on Control of Oral-Nasal Balance in Speech

<b><i>Introduction:</i></b> Previous research has shown that altering the nasal signal level auditory feedback changed the control of oral-nasal balance in normal speakers. The present study investigated whether knowledge of the task and the instruction not to compensate would change the participants’ response to the manipulation. <b><i>Methods:</i></b> Twenty participants (10 females) in 2 groups continuously repeated a sentence while their nasal signal level was increased or decreased and fed back to them via headphones, so the speakers heard themselves as more or less nasal, respectively. After the first recording session, participants were debriefed about the true nature of the experiment. They were instructed not to compensate in the second recording session. The outcome measures were the percentage changes of nasalance scores from the first baseline. <b><i>Results:</i></b> Statistical analysis using a repeated measures analysis of variance showed an effect of the nasal signal level, <i>F</i>(5,80) = 2.51, <i>p</i> = 0.049, and a nasal signal level by knowledge of task interaction effect, <i>F</i>(5,80) = 3.25, <i>p</i> = 0.019. Post hoc tests showed that the maximum nasal signal level auditory feedback resulted in a significant decrease of nasality from the initial baseline. <b><i>Conclusion:</i></b> Despite knowledge of the task, speakers were unable to resist compensating. As found in previous research, there was a numerically higher compensation response at the maximum than at the minimum nasal signal level auditory feedback condition.

The Effect of Nasalance on Vocal Fold Oscillation Patterns During the Male Passaggio

INTRODUCTION

It is generally assumed that when singing across the region where registration events for untrained voices occur (the passaggio), singers modify the voice production system in order to avoid changes of voice quality. In this context, it has been postulated that nasalance could be used to stabilize vocal function throughout the passaggio. However, whether nasalance is frequently used by professional singers and if so, if it has a stabilizing effect on vocal fold oscillation patterns, is not yet fully understood.

MATERIAL AND METHODS

Eight western classically trained professional male singers (6 tenors and 2 baritones) were asked to perform transitions (1) from modal to falsetto register and (2) from modal to stage voice above the passaggio (SVaP) during ascending pitch glides from A3 (ƒo approx. 220 Hz) to A4 (ƒo approx. 440 Hz) on the vowel /i/. Transnasal high-speed videoendoscopy at 20.000 fps was captured simultaneously with electroglottographic, nasal and oral flow, and audio signals, recorded using the same frame rate. The nasalance was calculated from both oral and nasal DC-flow signals.

RESULTS

Transitions to SVaP showed greater periodicity and regularity than transitions to falsetto. For 5 subjects, nasalance was increased during the passaggio for the transition to SVaP. For 4 subjects the increase of nasalance for the SVaP was associated with a stabilization of the open quotient and occurred at a comparable fundamental frequency as the increase of the open quotient for the transition to falsetto.

CONCLUSIONS

Nasalance can be used in order to stabilize oscillatory regularity and open quotient in male singers for singing across the passaggio.

Nasalization Amplitude-Timing Characteristics of Speakers With and Without Cleft Palate

OBJECTIVES

To examine the amplitude-temporal relationships of acoustic nasalization in speakers with a range of nasality and to determine the extent to which each domain independently predicts the speaker's perceived oral-nasal balance.

DESIGN

Rate-controlled speech samples, consisting of /izinizi/, /azanaza/, and /uzunuzu/, were recorded from 18 participants (14 with repaired cleft palate and 4 without cleft palate) using the Nasometer. The mean nasalance of the entire mid-vowel-nasal consonant-vowel (mid-VNV) sequence (amplitude-domain) and the duration of the nasalized segment of the mid-VNV sequence (temporal-domain) were obtained based on nasalance contours.

RESULTS

Strong linear and vowel-dependent relationships were observed between the 2 domains of nasalization (adjusted R² = 71.5%). Both the amplitude- and temporal-domain measures were found to reliably predict the speaker's perceived oral-nasal balance, with better overall model fit and higher classification accuracy rates observed in /izinizi/ and /uzunuzu/ than in /azanaza/. Despite poor specificity, the temporal-domain measure of /azanaza/ was found to have a strong correlation with the participants' Zoo passage nasalance scores (r_s = .897, p < .01), suggesting its potential utility as a severity indicator of perceived nasality.

CONCLUSIONS

With the use of relatively simple speech tasks and measurements representing the amplitude and temporal domains of nasalization, the present study provided practical guidelines for using the Nasometer in assessing patients with oral-nasal resonance imbalance. Findings suggest that both domain measures of nasalization should be examined across different vowel contexts, given that each domain may provide clinically relevant, yet different, information.

Comparison of nasal acceleration and nasalance across vowels

PURPOSE

The purpose of this study was to determine the performance of normalized nasal acceleration (NNA) relative to nasalance as estimates of nasalized versus nonnasalized vowel and sentence productions.

METHOD

Participants were 18 healthy speakers of American English. NNA was measured using a custom sensor, and nasalance was measured using the KayPentax Nasometer II. Speech stimuli consisted of CVC syllables with the vowels (//, /æ/, /i/, /u/) and sentences loaded with high front, high back, low front, and low back vowels in both nasal and nonnasal contexts.

RESULTS

NNA showed a small but significant effect of the vowel produced during syllable stimuli but no significant effect of vowel loading during sentence stimuli. Nasalance was significantly affected by the vowel being produced during both syllables and sentences with large effect sizes. Both NNA and nasalance were highly sensitive and specific to nasalization.

CONCLUSIONS

NNA was less affected by vowel than nasalance. Discrimination of nasal versus nonnasal stimuli using NNA and nasalance was comparable, suggesting potential for use of NNA for biofeedback applications. Future work to improve calibration of NNA is needed to lower intersubject variability.

Acoustic features for identifying constitutions in traditional Chinese medicine

OBJECTIVES

Constitutions are Traditional Chinese Medicine syndromes that are used to classify symptoms. The present study sought to identify objective acoustic features for eight commonly occurring abnormal constitutions.

METHODS

Speech signals were obtained from 281 subjects through a 1-second vowel sound, /a/, uttered by the subjects. For each constitution, differences in acoustic parameters between the low-score and high-score groups were compared.

RESULTS

Subjects in the high-score groups for Yin-deficiency, Qi-deficiency, Phlegm-wet, Blood-stasis, and Qi-depression showed lower acoustic intensities than subjects in the corresponding low-score groups (all p<0.05). Subjects in the high-score groups of Qi-deficiency and Blood-stasis exhibited higher maximum pitches and higher minimum pitches than subjects in the low-score groups (all p<0.01). The average number of zero-crossings was lower in the high-score groups of Qi-deficiency and Blood-stasis than in the low-score groups for both constitutions (p<0.05). Subjects in the high-score group of special diathesis demonstrated higher low-spectral-energy ratios than subjects in the low-score group (p<0.05), and subjects in the high-score group of Blood-stasis had higher middle spectral energy ratios than subjects in the low-score group (p<0.05). In contrast, the middle spectral energy ratio in the high-score group of special diathesis was lower than in its corresponding low-score group (p<0.05). The high spectral energy ratios were lower in the high-score groups for Yin-deficiency and Blood-stasis (both p<0.05) than in the low-score groups.

CONCLUSIONS

The present study identified acoustic features for constitutions and established objective methods for constitutional diagnosis. These acoustic features can potentially be applied in the expert system of Traditional Chinese Medicine for the diagnosis of constitutions in the general population.

Inverse filtering of nasalized vowels using synthesized speech

The present study examines the extent to which increased nasal coupling affects estimates of glottal parameters derived from inverse filtering based on an all-pole assumption of the vocal tract. A series of steady-state tokens for five Swedish vowels were synthesized using the HLsyn quasi-articulatory synthesizer (Sensimetrics, Malden, MA). For each vowel, the parameter controlling the cross-sectional area of the nasal aperture, an, was systematically varied, while the other HLsyn parameters were kept constant. The resultant pressure signal for each utterance was subsequently inverse filtered, and estimates were made of five glottal source parameters (EE, RG, RA, RK, and OQ) derived from fitting the Liljencrants and Fant source model to the inverse filtered signal. The results show that when analyzing nasalized vowels using inverse filtering based on an all-pole assumption of the vocal tract, the RA parameter estimate--a main determinant of the source spectral slope--can be adversely affected by nasal coupling. The errors in our estimates were particularly high for the high vowels: this was true not only for RA, but for all the parameters measured. However, with the exception of the distortion in the RA estimate, the effects were relatively small, regardless of the degree of nasal coupling.

Effects of computer system and vowel loading on measures of nasalance

PURPOSE

The purpose of this study was to determine similarities and differences in nasalance scores observed with different computerized nasalance systems in the context of vowel-loaded sentences. Methodology Subjects were 46 Caucasian adults with no perceived hyper- or hyponasality. Nasalance scores were obtained using the Nasometer 6200 (Kay Elemetrics Corp.), the Nasometer II 6400 (Kay Elemetrics Corp.), and the NasalView (Tiger DRS, Inc.) for sentences loaded with mixed, high front, high back, low front, or low back vowels.

RESULTS

Measures of nasalance obtained with the NasalView were significantly higher than those obtained with the Nasometer 6200, and the measures of nasalance obtained with the Nasometer 6200 were significantly higher than those obtained with the Nasometer II 6400. However, similar effects of vowel loading on measures of nasalance were observed, regardless of system. For all systems, the high front vowel sentence tended to result in higher measures of nasalance than did the high back, low front, and low back vowel sentences--the mixed vowel sentence tended to have a higher degree of nasalance than did any of the other sentences.

CONCLUSIONS

Although nasalance data computed using different systems are not readily comparable, all three systems that were evaluated produced similar effects of vowel loading on nasalance. Increased nasalance for high front versus low back vowels may be due to factors such as increased oral impedance, reduced radiated oral sound pressure, possible increases in airflow via the nasal cavity, and increased transpalatal nasalance.