About this app

Special feature of the Pro version:
After successful statistical analysis, the graphical bar display is green, on failed evaluation it is shown red. To differentiate graded color combinations are used. The numerically displayed average includes the frequencies from 250 Hz to 5000 Hz. In the average only the results with green bars are considered. These are considered sufficiently statistically safe. With the button - and the button + decay curves of all frequencies can be displayed.

The numerical value of the reverberation time, standing on the far right, is denoted by Z (Z for Zero). Here no frequency analysis or frequency weighting takes place. This value is displayed in the standard version of the APP.


General:

With this app, the reverberation time of a room can be measured.

The reverberation time is an acoustic parameter for the reverberation of a room. It is described by the drop in sound pressure level which is measured after a short loud noise (pop a bag or clap your hands once). The time it takes for the sound to decay by 60 dB, is called the reverberation time.

When assignment "= 80 dB loud" and "20 dB = quiet" you can also say this: The reverberation time is the time that elapses until you no longer observe a previously loud noise.

In a classroom at school or a in a kindergarten, the reverberation time should be about 0.6 seconds. The desirable value is slightly dependent on the volume of the room: 180 m³ = 0.55 s / 360 m³ = 0.65 s.

The value of 0.6 seconds is considered for a full room with students or children. Due to the absorption of the bodies, the reverberation time of an empty room is higher. For an empty room the reverberation time should be 0.75 seconds, instead of the 0.6 seconds for a full room.

For hearing-impaired children or adults with tinnitus the nominal reverberation time can be reduced by 20%.

For comparison: In a room, which is used for music, the reverberation time should be 1.1 seconds, in churches, the value is 2 seconds or higher.

The reverberation time is too long:
In a live room every word sounds louder. Furthermore, a previously spoken word is still audible when the following words are spoken. They talk across each other. To improve the speech intelligibility the speaker speaks louder. Thus, it becomes even louder in the room.

The reverberation time is too short:
Children, standing directly in front of the speaker, understand the spoken words well. Due to high sound absorption in the room, on the side and particularly in the rear area of the speaker, the words are bad to hear. The children do not feel addressed. This can be compensated by speaking louder, but this leads to hoarseness of the speaker.

Measurement of the reverberation time:
Before and during the measurement, it must be quiet in the room. The measurement is triggered by a loud clap or popping of a paper bag. The determined value of the reverberation time is displayed immediately. For evaluating the average of 3-5 measurements should be used.

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