Towards better sound services for elderly listeners, we investigated relative differences among daily averaged sound levels of fifteen TV channels in Japanese terrestrial and BS digital broadcasting. Abrupt sound level change at the instant when listeners turn over, sometimes give intense discomfort for them, especially for elder listeners, because their auditory dynamic ranges tend to be narrower, and their abilities to discriminate the speech from background noises are decreasing. The results

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... show that there is a clear difference of the sound levels between the terrestrial and the BS digital broadcasting. The daily averaged sound level of the terrestrial TV channels was about-6.1 dB which was 4dB higher than that of BS digital TV channels. The variance of the average in the terrestrial channels was 5dB smaller in BS digital channels. The sound levels of over 50% programs in three terrestrial channels, were-5dB. The fact that the sound levels of some TV channels are concentrated to higher levels with the small variance implies that the sounds will often annoy elder listeners even if the average level differences would be small. We also measured the relative sound levels every 5 sec over 21 hours across the terrestrial and BS digital TV channels. The maximum level, the minimum level and the average level across the channels at a certain time were picked up. The maximum levels over 21 hours were averaged, resulting in-2.6 dB with the variance of 1.3 dB. The minimum levels, on the contrary, were distributed over a wide range. This implies that there will be not a few cases that abrupt sound level change annoying elderly listeners will occur.