Methodology for quantifying perceptual effects from noise suppression systems

• Published in: International journal of audiology 2005-12, Vol.44 (12), p.721-732
• Main Authors: Dahlquist, Martin, Lutman, Mark E., Wood, Sally, Leijon, Arne
• Format: Article
• Language: English
• Subjects: Acoustic Stimulation - methods; Algorithms; Audiometry, Speech; Auditory Perception - physiology; Female; Hearing Loss - physiopathology; hearing-aid effectiveness; Humans; Male; Noise - adverse effects; noise reduction; paired comparisons; Perceptual Masking; sound quality; Speech Perception - physiology
• ISSN: 1499-2027; 1708-8186; 1708-8186
• DOI: 10.1080/14992020500271712

Methodology is proposed for perceptual assessment of both subjective sound quality and speech recognition in such way that results can be compared between these two aspects. Validation is performed with a noise suppression system applied to hearing instruments. A method termed Interpolated Paired Comparison Rating (IPCR) was developed for time efficient assessment of subjective impression of different aspects of sound quality for a variety of noise conditions. The method is based on paired comparisons between processed and unprocessed stimuli, and the results are expressed as the difference in signal-to-noise ratio (dB) between these that give equal subjective impression. For tests of speech recognition in noise, validated adaptive test methods can be used that give results in terms of speech-to-noise ratio. The methodology was shown to be sensitive enough to detect significant mean differences between processed and unprocessed speech in noise, both regarding subjective sound quality and speech recognition ability in groups consisting of 30 subjects. An effect on sound quality from the noise suppression equivalent to about 3-4 dB is required to be statistically significant for a single subject. A corresponding effect of 3-6 dB is required for speech recognition (one-sided test). The magnitude of difference that occurred in the present study for sound quality was sufficient to show significant differences for sound quality within individuals, but this was not the case for speech recognition. Sumario Se propone una metodología para la evaluación perceptual tanto de la calidad subjectiva del sonida como del reconocimiento del lenguaje, de tal forma que dichos resultados puedan ser comparados entre sí. La validación se realizó con un sistema de supresión de ruido aplicado a dispositivos auditivos. Se desarrolló un método Ilamado Puntaje Interpolado Comparativo Pareado (IPCR) para una evaluación tiempo-eficiente de la impresión subjectiva de diferentes aspectos de la calidad del sonido para una variedad de condiciones ruidosas. El método está basado en comparaciones pareadas entre estímulos procesados y no procesados, y los resultados se expresan como la diferencia en la tasa señal/ruido (dB) entre estos, que produce una impresión subjetiva igual. Para las pruebas de reconocimiento del lenguaje en ruido, se pueden utilizar métodos de evaluación adaptativa validados, que rindan los resultados en términos de tasas de lenguaje/ruido. La metodología mostró que es l