Long-term spectra of a range of real-life noisy environments

The long-term spectra of 13 everyday background noises were examined and compared to the long-term spectra of speech at three different levels: 1) 54.5 dB SPL (casual conversation), 2) 70 dB SPL ('normal'), 3) 83.3 dB SPL (shouting speech). The background noises comprise babble-noises at three different levels, noise from inside four different means of transport, some outdoor noises (noise from passing traffic, noise from passing aircraft, and city noise), and some indoor noises (office noise, television or radio, and washing up). All noise samples masked the casual speech in both the low and the high frequencies. In relation to the 'normal' speech level, a majority of the noise samples appeared to be most intrusive in the low frequencies. Apart from extremely loud babble-noise, the various background noises only masked the shouting voice in the low frequencies. Implications of the findings for multiple memory hearing aids are discussed.