Normalized Noise Energy Research Articles

Acoustic measurements and perceptual evaluation of hoarseness in children's voices

According to a previous investigation of children's voices hoarseness was found to be a stable concept consisting of three main predictors: hyperfunction, breathiness, and roughness. The present investigation analyzes the relation between these perceptual voice characteristics, complemented by instability and gratings (high pitched roughness) on the one hand and four acoustic measures: pitch perturbation quotient, amplitude perturbation quotient and two types of normalized noise energy measures on the other. The analysis was carried out on a sample of vowels sustained by 50 ten-year-old school children representing different degrees of hoarseness. Significant correlations were found between hoarseness, breathiness, and roughness, and two acoustic measures, namely a frequency perturbation quotient and one harmonics-to-noise measure.

気管食道科領域における鏡視下手術 気道系 喉頭の鏡視下手術―良性腫りゅう性病変を中心として

In our clinic, laryngo-micro surgery under general anesthesia with endotracheal intuba- tion or neurolept analgesia without intubation (NLA) have been commonly practiced for the surgical treatment of voice disorders due to polyps or polypoid degeneration of the vocal cords. Here we report the differences in postoperative phonatory functions caused by anesthesia with/without intubation. Laryngo-micro surgery (under anesthesia with intubation: 17, NLA : 14) was performed on 31 cases (16 polypoid, 15 polyps). After operation, the maximum phonation time (sec), air flow rate (ml/sec), pitch (Hz), pitch perturbation quotient (%), amplitude perturbation quotient (%), and normalized noise energy (dB) were obtained using a phonatory device PS-77 and an acoustic analyser SH-10. No significant differences were observed between the phonatory parameters in the NLA group and those in the intubation group. However, in the phonatory parameters of the NLA group, there were more normalized mean values and smaller standard variations than in the intubation group. From these results, we conclude that laryngo-micro surgery under NLA has the advantage of producing a stable postoperative phonatory effect, since it provides a good chance to observe the vocal cords' vibrations and to make an acoustic evaluation of the voice in the course of an operation.

Measures of vocal function during changes in vocal effort level

The purpose of this article is to present the results of a controlled study of the day-to-day variabilities of three acoustic parameters (jitter, shimmer, and normalized noise energy), and two electroglottographic parameters (contact quotient and contact quotient perturbation) for vowels produced at three vocal efforts (low, normal, high). Data were obtained with use of a sophisticated bilinear interpolation pitch detection method. A repeated measures design required subjects to produce the vowels /ae/ and /a/ five times a day over 3 days at each vocal effort level. The jitter, shimmer, and normalized noise energy values from acoustic measures and contact quotient and contact quotient perturbation values varied significantly among the three vocal effort levels. The clinical implication of this finding is that vocal effort must be controlled in order to obtain consistent clinical measures. Furthermore, day-to-day variability must be taken into account if representative measures are to be obtained for clinical use.

Quality analysis of laryngography in a busy hospital ENT voice clinic.

The Portable Laryngograph provides a non-acoustic plot of wet mucosal contact at the glottis over the vocal fold vibrational cycle called the Lx waveform in Laryngograph terminology. Although well-equipped clinics gain most ENT requirements for investigation from the video endoscope, the nature of stroboscopy prevents the investigation over single glottal periods and many transitory problems may be missed. A high-quality Lx signal waveform will reflect any irregularities in mucosal contact and substantially complements the endoscopy examination. Yield, however, is a problem in the environment of an ENT hospital voice clinic. In this topic paper the criterion of maximum acceptable normalised noise energy (NNE) = -15 dB is used to assess the quality of 61 Laryngograph measurements. By this criterion a pass rate of 78% was achieved. This is considered to be good within an ENT voice clinic population where voice problems are in fact the dominant reason for referral.

T1b声門癌CO<SUB>2</SUB>レーザー手術

Phonatory functions were compared among 25 patients with T1 glottic cancer (T1a : 18, T1b : 7) following the combined therapy of laser and radiation, 9 patients with T1-2 following radiation treatment alone, and 40 normal subjects (over 50 years old). Maximum phonation time (sec), air flow rate (ml/sec), vocal velocity index, pitch (Hz), pitch perturbation quotient (%), amplitude perturbation quotient (%), and normalized noise energy (dB) were obtained from the use of a phonatory equipment PS-77 and an acoustic analyser SH-10.Moreover, phonatory dysfunctions in 6 of 7 patients with T1b glottic cancer were estimated on the basis of extent and depth of laser irradiation, and of post-operative laryngeal findings by fiberscope.The results were as follows.1. The mean values of phonatory parameters in normal subjects were MPT : 17.8 sec, AFR : 187 ml/sec, VVI : 45.5, pitch : 147 Hz, PPQ : 1.01%, APQ : 3.34%, and NNE : -11.1 dB respectively.In comparison with the normal subjects, those values of radiation treatment alone coinsided closely, and those of T1 group indicated distinctly a decline of the aerodynamic functions and a change for the worse of the acoustic characteristics of voices. However, the difference of those parameters were statistically no significant between Tla and Tlb group.2. After CO2 laser surgery for T1b, laryngoscopy revealed web formation of the anterior commissure (28%), asynmetry and fibrosis of all affected vocal cords. Degree of the post-operative changes had been affected by the extent more than the depth of laser irradiation in glottis.3. In T1b group, the mean values of phonatory parameters in the 3 patients with a marked postoperative change were a short MPT (6.2 sec), higher AFR (372 ml/sec) and VVI (104.3), and pitch : 225 Hz, PPQ : 1.79%, APQ : 4.00%, NNE : -5.6 dB, while, those in the 3 with a mild change were MPT : 18.0 sec, AFR : 155 ml/sec, VVI : 34.1, pitch : 146 Hz, PPQ : 0.25%, APQ : 2.56%, NNE : -14.2 dB, respectively.Because of having the lesion in both vocal cords, CO2 laser management for T1b glottic cancer has including more complex problems than that for T1a in the insure of favorable post-operative voices. At least, laser irradiation covered wide range of the bilateral vocal cords may be phonetically disadvantage. In the use of CO2 laser, it is a necessary to control adequately the extent of laser irradiation in a combination with radiation therapy of curative dose.

Vocal function in patients with unilateral vocal fold paralysis before and after silicone injection.

A total of 240 patients with unilateral vocal fold paralysis (UVFP) underwent transcutaneous intrafold silicone injection (TCIFSI) for the purpose of vocal rehabilitation during the period from 1983 to 1993 in the Kurume University Hospital. Their vocal function was evaluated and the effects of TCIFSI upon the vocal function were investigated. The patients with UVFP presented with an increase in airflow during phonation; a decrease in maximum phonation time and fundamental frequency (F0) range and sound pressure level (SPL) range of phonation; and an increase in pitch perturbation quotient, amplitude perturbation quotient and normalized noise energy in the voice signal. TCIFSI resulted in a decrease in airflow, an increase in phonation time and F0 and SPL range of phonation, and a decrease in pitch and amplitude perturbation and noise in the voice signal. Patient's own subjective evaluation presented with an improvement of his/her voice after TCIFSI.

Acoustic analysis of functional dysphonia: Before and after voice therapy (accent method)

Ten patients who were referred to a speech pathologist for functional voice disorders were treated with voice therapy using the accent method. The vocal folds were normal except in three females who had moderate bilateral nodules. The voices were analyzed acoustically before and after treatment. Of the parameters tested, pitch perturbation quotient, amplitude perturbation quotient, normalized noise energy for 1-4 kHz, and fundamental frequency showed significant improvement.

Sulcus Vocalis: Functional Aspects

The vocal function of 126 patients with sulcus vocalis was evaluated with the use of a test battery of multidimensional evaluation items. Of the 126 patients, 31 had a unilateral sulcus and 95, bilateral lesions. The results were as follows. 1) The majority of the patients had a mild degree of hoarseness with a breathy quality. 2) An incomplete glottic closure, a small vibratory amplitude, and a small mucosal wave were frequently observed in the stroboscopic examination. 3) The maximum phonation time, fundamental frequency range, and sound pressure level range of phonation were decreased, whereas the airflow during phonation was increased. 4) The pitch perturbation quotient, amplitude perturbation quotient, and normalized noise energy were increased. 5) Abnormal test results were more frequent and more marked for bilateral lesions than for unilateral lesions.

Transcutaneous Intrafold Injection for Unilateral Vocal Fold Paralysis: Functional Results

This paper presents the technique of transcutaneous intrafold silicone injection and the functional results of 44 procedures in 42 patients. The injection is given under local anesthesia with the patient in a supine position. The needle is inserted through the cricothyroid space. The location of the needle as well as the effect of injection is monitored by means of a fiberscope connected to a television camera and screen. The preoperative and postoperative vocal function was multidimensionally evaluated with the use of a test battery consisting of the maximum phonation time (MPT), mean airflow rate (MFRc), fundamental frequency (F0) range and sound pressure level (SPL) range of phonation, pitch perturbation quotient (PPQ), amplitude perturbation quotient (APQ), and normalized noise energy (NNEa). In the majority of the patients, MPT, F0 range, and SPL range increased and MFRc, PPQ, APQ, and NNEa decreased postoperatively. In the overall evaluation based on the test values of these parameters, the result was excellent for 16 procedures, good for 16, fair for 7, and poor for 5. The most frequent cause of failure was an insufficient amount injected.

声帯ポリープにおける病変の程度と音声検査成績との関係

Relationships between the degree of lesion and that of vocal dysfunction were investigated in 122 cases of vocal fold polyp. A normalized size of polyps and glottic gap were correlated to the results of phonatory ability tests, stroboscopic investigations, acoustic analyses, and perceptual evaluations. There was no significant correlation between the size and the gap. The size of polyp was negatively correlated to fundamental frequency, whereas it was positively correlated to roughness of voice, asymmetry of vocal fold vibration, irregularity of vocal fold vibration, pitch perturbation quotient, amplitude perturbation quotient, and normalized noise energy. The glottic gap showed negative correlations to maximum phonation time and sound pressure level, and positive correlations to mean airflow rate and fundamental frequency.

Falsetto, head/chest, and speech mode: An acoustic study with three tenors

<h2>Summary</h2> An acoustic analysis of voices in falsetto, head/chest, and speech mode produced by three tenor singers was conducted. The three different modes of phonation were produced at a fairly high pitch in five Japanese vowels. The results were as follows: (a) pitch period perturbation quotient was smaller in speech than in head/chest and falsetto, (b) amplitude perturbation quotient was smaller in speech than in falsetto, (c) normalized noise energy was smallest in falsetto and greatest in head/chest, (d) gross spectral decay between 0 and 4.5 kHz was greatest in falsetto and smallest in head/chest, (e) singing formant was remarkable both in head/chest and speech, and (6) the speech mode was associated with relatively strong harmonics in high-frequency range between 3.5 and 4.5 kHz.

Characteristics of normalized noise energy(NNE) for the detection of pathological voice.

Characteristics of normalized noise energy(NNE) for the detection of pathological voice.

Perceptual significance of a vocal noise measure for the evaluation of pathological voice

By using a comb filter, harmonic components in a sustained vowel have been separated from the vocal noise which is primarily associated with the turbulent noise produced at the glottis due to insufficient closure of the vocal folds [H. Kasuya et al., Proc. ICASSP-86, 669–671 (1986)]. An acoustic measure, normalized noise energy (NNE) is then defined on the extracted noise signal, by measuring the relative level of the noise energy to that of the original voice. The NNE has shown better detectability of pathological voice status than jitter and shimmer parameters. This paper investigates the relation between the NNE and perceived qualities of hoarseness of a pathological voice, as “hoarseness grade” and “breathiness.” From the experiments we conclude that the NNE is related to the perceptual qualities of a pathological voice much better than jitter and shimmer parameters and some other noise measures do. [Work supported by a Japanese Grant-in-Aid for Scientific Research.]

Normalized noise energy as an acoustic measure to evaluate pathologic voice.

In order to evaluate noise components included in pathologic voice signals, a novel acoustic measure, normalized noise energy (NNE), is proposed and its effectiveness for the detection of laryngeal pathologies is investigated with 250 vowel samples spoken by 64 control (normal) subjects and 186 patients with various laryngeal diseases. The NNE is automatically computed from the voice signals using an adaptive comb filtering method performed in the frequency domain. Experiments with the voice samples show that the NNE is especially effective for detecting glottic cancer, recurrent nerve paralysis, and vocal cord nodules. Specifically, when glottic cancer is represented in terms of the T classification adopted by the UICC (Union Internationale Contre le Cancer), glottic T2-T4 cancer can be perfectly discriminated from normal samples, but 22.6% of patients with glottic T1 cancer are incorrectly classified as normal, with an error rate of 9.4% for normal subjects.