Seeing, heading and understanding the whole.
The acoustic characteristics of a room essentially determine the usage and influence the well-being, the communication, the creative exchange of ideas and the concentration of employees.
Sound pressure level, reverberation time and speech intelligibility are the parameters that can be made visible by acoustics measurement. Being a specialist for acoustic solutions we can offer you acoustics measurement according DIN 18041 and DIN 3382.
Our trained employees carry out the measurements and will present a detailed report evaluating the results.
Based on the measurements we work closely with you to devise solutions for improving room acoustics.
The sound pressure level
Noise is a result of vibrations and they transmit in form of sound waves in the air. The intensity of sound – the volume – can be measured. The measured variable is known as sound pressure, the displayed measurement value is the sound pressure level which is measured in decibels (dB). The decibel scale has a logarithmic structure. This allows to register the sound intensity from the relative value 1 (threshold of hearing) up to the value of 10 trillions (pain threshold)·into values from at 0 to 130 dB. Therefore an increase of 10 dB corresponds to a tenfold increase in the sound’s intensity.
A sound event can be described as the lowest pressure variation around the atmospheric pressure; this vibration is is perceived by the hearing. Between the hearing threshold and pain barrier the human hearing has a surprisingly high range in perception of the sound pressure level.
However, the more powerful a sound is, the more people perceive it as an unpleasant noise. Noise comprises all sound events which affect human well-being.
Therefore the term noise is a subjective, only the (described by physics) sound is measurable. Loud and lasting noise emissions considerably reduce the performance and can even make you sick.
The reverberation time
The most important physical quantity used to describe the acoustical properties of a room is its reverberation time. The reverberation time is determined by knowledge of the sound decay in a certain room over time. More precisely it is defined as the time (in seconds) that it takes for the sound level to decay by 60 dB after the sound impulse has stopped producing the sound. The reverberation time is directly depending on the size and geometry of a room, the sound-absorbing characteristics of the room surfaces and the interior design.
Reverberation arises through repeated reflection of sound at the room boundary surfaces.
A listener in a room not only perceives the direct sound but numerous acoustic echoes i.e. sound components after single and multiple reflections. In comparison to direct sound the reflections are delayed and weakened because they have to travel longer paths and reflection is reduced at walls and other surfaces. We experience a room with a long reverberation time as reverberant.
You will find a higher sound pressure level in this room and can, for example, result in strong disturbances in working areas.
The faster the acoustic signal decreases in a room the less strenuous it will be for people to work concentrated in this room.
The speech intelligibility
In terms of room acoustics, speech intelligibility is a well-defined concept which indicates how well speech is perceived in a room – either directly with a speaker and a number of listeners or via a sound system with a microphone, amplifier and speaker(s).
Traditionally, speech intelligibility has simply been measured by listing how many words listeners have heard correctly in a text which is read out loud by an articulate speaker in the room in question.
If the listeners, for example, hear 60 per cent of the words correctly, the speech intelligibility is 60 per cent or 0,6. Obviously, this method did not produce any objectively reproducible results.
A widespread measurement and analytical methods which is now regarded as the standard approach is the so-called Speech Transmission Index (STI). The STI takes certain parameters about the room into account and provides a measured value that shows the given circumstances of speech intelligibility in an easily interpretable value between 0 an 1. In practice values between 0,35 (virtually unintelligible ) to 0,75 (very intelligible) are customary.
Using a simplified procedure called STIPA (STI for PA – Public Adress) today handheld level meters are measuring the speech intelligibility.