Music Dynamic Levels

Note: This C₆ at 1024 Hz is the nominal "scientific" C often found with tuning forks produced by science equipment companies. The modern C₆ in the equal tempered scale based on A₄ = 440 Hz is C₆ = 1046.5 Hz.

Early Rock Concert

The author was commissioned to do survey measurements of outdoor rock concerts in the 70's when the sound equipment being used was incapable of wide dynamic ranges. Measurements for a given concert were:

These were the entire dynamic ranges of the concert! Even with changes in vocals and instruments, the overall sound level hardly changed. The amplifications systems of the day were often operated with some feedback to get to the loud levels desired. Much more dynamic range exists in more modern amplified concerts. Differences of 10-12 dB between the A contour and flat measurements have been found to be fairly typical for outdoor concerts. Differences can be much more pronounced for indoor measurements.

Orchestra Children's Concert

The measurement of the variety of music in an orchestra concert for children gives some insight into the nature of sound measurement in straight decibels versus measurement with an A contour meter. The following measurements were made:

Comments: Orchestra Concert

The similar measurments using the A Contour and flat decibels attest to the hardly surprising fact that the children's noises are almost completely in the maximum sensitivity region of human hearing where the A contour does not attenuate the sound. The fact that the orchestral instruments also gave very similar readings in dBA and dB attests to the efficiency of these instruments in producing only audible sound and wasting little energy with inaudible low or high frequencies. Again, this is hardly surprising considering that these instruments have been refined as musical sound sources for hundreds of years. The overall similarity of dB and dBA in a concert hall indicates that the builders did a good job of isolating the music-making area from the low frequency sounds characteristic of air conditioning and heating systems which would have increased the dB readings relative to the dBA measurements. Another notable fact about the concert is the wide dynamic range of the orchestral range - 30 dB or more compared to a much smaller range for some amplified concerts.