decibels (dB) understand: Volume, scale & apps explained
Definition: What does decibel mean?
A decibels (dB) describes one relationship between two values – usually volume or electrical power. It is based on a logarithmic scale: An increase of +10 dB is known as Doubling the loudness felt.
0 dB SPL corresponds to the hearing threshold.
130 dB SPL is the pain threshold.
Everything about 85 dB SPL can cause permanent hearing damage (BfR warning).
How does the decibel scale work?
The scale is logarithmic built up – i.e. an increase of 10 dB corresponds to one 10 times Increase in energy, but is only perceived as twice as loud.
Examples of sound levels:
| noise | Sound level (dB SPL) |
|---|---|
| To breathe | about 10 dB |
| to whisper | about 30 dB |
| Normal entertainment | about 60 dB |
| road traffic | about 80 dB |
| Rock concert / club | 110-120dB |
| Airplane takeoff (close) | 130-140dB |
What decibel units are there?
In the audio sector, different dB variants are used – depending on the application:
dB SPL: Sound level related to air pressure – for physical volume.
dB (A): Rated according to the Sensitivity of human hearing (A-filter).
dB FS (Full Scale): Reference value in the digital audio technology, maximum value = 0 dBFS.
dBu / dBV: Refer to electrical voltages – especially in the studio.
Bel and Neper: Obsolete or in special areas (e.g. communications engineering).
👉 Tip:: For mixing and mastering, dBFS crucial, as this is where the maximum digital headroom is defined – read our article on Clipping and dBFS.
How can you measure volume in decibels?
Sound levels can be measured using the following tools:
Professional sound level meter (accurate, calibratable)
Decibel app on the smartphone (approximate values only)
Application: Hold the microphone at ear level to the sound source and pay attention to ambient noise. For reliable measurements, a calibrated measuring device Mandatory – e.g. for workplaces or event venues (Source: BAuA).
Can I measure decibels with the iPhone?
Yes – modern iPhones (from iOS 13) have a built-in volume measurement in the Health app. There are also third-party apps such as:
Decibel X (iOS + Android)
NIOSH Sound Level Meter (iOS, very precise)
Sound Meter PRO (Android)
These apps are practical for rough estimates, but do not replace a calibrated measuring device.
How good are decibel apps?
Decibel apps use the built-in microphone of the smartphone – this is not calibrated and often has limited frequency ranges. Nevertheless, they are sufficient for:
Noise assessments in everyday life
Monitoring during band rehearsals
initial assessments of hearing strain
You should do professional audio work never rate exclusively via app.
Why is decibel so important in audio production?
The decibel indication helps you to correctly estimate levels, avoid clipping and to objectively compare sound conditionsWhether it's microphone level, headroom in the master, or dBFS during export – nothing works in the recording studio without dB.
🔍 Read more:
Frequently asked questions about decibels
What does 0 dB mean?
0 dB SPL is the threshold of hearing – the quietest sound a person can perceive.
How many dB are harmful to hearing?
Hearing damage is at risk at 85 dB SPL for extended periods. At 120 dB, damage can occur even in the short term.
What is the difference between dB SPL and dB FS?
dB SPL measures physical volume in the air, dB FS measures digital signal strength in the audio file.
Which app measures decibels most accurately?
The app NIOSH SLM (iOS only) is considered particularly precise because it is based on professional standards.
Does twice as loud mean twice as many dB?
No – a doubling of the loudness is achieved at about +10 dB perceived, technically this corresponds to a 10 times Increase in energy.