Wilson 2 evaluated more than 3,400 veterans. Therefore, for the person who needs an 8 dB SNR, we subtract 2 dB (normal performance) from their 8 dB score, resulting in a 6 dB SNR loss. He reports people with relatively normal/typical SNR ability may require a 2 dB SNR to understand 50% of the sentences spoken in noise, whereas people with mild-moderate sensorineural hearing loss may require an 8 dB SNR to achieve the same 50% performance. Killion defines SNR loss as the increased SNR needed by an individual with difficulty understanding speech in noise, as compared to someone without difficulty understanding speech in noise. Killion 1 reported people with substantial difficulty understanding speech-in-noise may have significant “SNR loss.” Of note, the SNR loss is unrelated to, and cannot be predicted from, the audiogram. The essence of the SIN problem is that the primary speech sounds and secondary sounds (ie, noise) are essentially the same thing! That is, both speech and speech babble noise originate with human voices with similar spectral and loudness attributes, rendering the “SIN” problem difficult to solve. “Speech” (in this article) is the spoken signal of primary interest and “noise” is the secondary sound of other people speaking (ie, “speech babble noise”). 1 That is, the goal is to make it easier for the brain to identify, locate, separate, recognize, and interpret speech sounds.
To provide maximal understanding of speech in difficult listening situations, the goal of hearing aid amplification is twofold: Make speech sounds audible and increase the signal-to-noise ratio (SNR). The amount of distortions vary, and listening results are not predictable based on an audiogram, nor are they predictable based on word recognition scores from speech in quiet. As hearing loss progresses from mild (26 to 40 dB HL) to moderate (41 to 70 dB) and beyond, distortions increase, disrupting spectral, timing, and loudness perceptions. Hearing is the ability to perceive sound, whereas listening is the ability to make sense of, or assign meaning to, sound.Īs typical hearing loss (ie, presbycusis, noise-induced hearing loss) progresses, outer hair cell loss increases and higher frequencies become increasingly inaudible.
The primary issue is understanding speech-in-noise (SIN). The most common problem experienced by people with hearing loss and people wearing traditional hearing aids is not that sound isn’t loud enough. Beck, AuD, and Nicolas LeGoff, PhD A discussion of signal-to-noise ratio problems and solutions, and a summary of findings of a study involving Oticon Opn hearing aids. Tech Topic | September 2017 Hearing Reviewīy Douglas L.
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