What does enabling absolute volume do?

What is Absolute Volume?

Absolute volume is defined as the objective loudness of audio expressed in decibels (dB). It refers to the actual voltage level or sound pressure level that is reproduced by speakers or headphones1. Absolute volume measures the physical intensity of the sound waves without accounting for any software adjustments or perceived loudness by the human ear.

This differs from relative volume, which is the user-adjustable volume level set within a software application or device. Relative volume is a subjective perception of loudness that can vary between different listeners. Absolute volume provides a fixed reference point to measure volume regardless of hardware or software factors.

Absolute volume is important in audio production and playback because it allows audio levels to be calibrated to known loudness standards. This helps ensure consistent volume across different content, devices, and listening environments. Setting absolute volume correctly helps prevent excessively loud or quiet playback.

How Absolute Volume Works

Absolute volume is measured in decibels (dB) for analog audio and decibels relative to full scale (dBFS) for digital audio. The maximum absolute volume level for analog audio is typically around 120 dB, which is the threshold of pain for the human ear. The maximum level for digital audio is 0 dBFS, which refers to the maximum sample value possible given the bit depth. For 16-bit audio, the maximum sample value is 32767, corresponding to 0 dBFS.

Audio devices calculate absolute volume by converting the digital or analog signal level to dB or dBFS units. This conversion requires knowing the reference level, which is the loudest sound that can be represented. For analog audio, the reference is standardized at 0.775 VRMS. For digital audio, the reference is the maximum possible sample value (32767 for 16-bit). The device measures the signal level compared to the reference to determine the absolute volume in dB/dBFS.

By reporting volume in absolute units rather than a relative percentage, absolute volume provides a consistent listening experience across different audio devices and content. The volume level in dB/dBFS directly corresponds to the actual acoustic intensity heard by the listener.

Enabling Absolute Volume

Enabling the absolute volume feature on Android devices ensures that the volume level stays consistent when switching between audio sources or content. With absolute volume enabled, the OS takes control over the volume rather than having each audio app control volume independently. This prevents the sudden volume spikes or drops that can occur when switching between apps or media.

When enabled, absolute volume works by setting the output volume level to a fixed percentage based on the system volume slider. This volume level is then applied to all audio output universally, regardless of the source. For example, switching from listening to music to watching a YouTube video will maintain the same loudness rather than having two different volume levels for each app. The volume is “absolute” in the sense that it remains steady rather than changing with each audio source.

According to Business Insider, enabling absolute volume synchronizes the volume control between the phone and any connected Bluetooth devices. Adjusting the volume on one will change it on both, preventing the need to adjust the volume separately on each device.

Benefits of Absolute Volume

One of the main benefits of enabling absolute volume is that it prevents jarring volume jumps between songs or videos. With absolute volume, the volume level is based on perception rather than pure decibel level. This means that two songs mastered at different loudness levels will play at the same perceived volume rather than the same raw decibel level. As a result, you won’t get blasted by a suddenly loud song after a quiet one when using absolute volume.

As this article explains, absolute volume “offers much better audio control than Bluetooth volume alone.” By taking the human perception of volume into account, absolute volume provides a more consistent and comfortable listening experience. The volume level will be determined by how loud it actually sounds to you rather than just the decibel measurements. This prevents abrupt volume spikes that can be fatiguing or even damaging to your hearing.

Drawbacks of Absolute Volume

While enabling absolute volume provides more granular control, there are some drawbacks to be aware of:

Can reduce dynamic range of audio

With absolute volume enabled, the full dynamic range of audio playback may be reduced. This means the difference between the loudest and softest parts of music or video can be compressed. Some nuances in audio detail may be lost. According to testing by Nikitajaniya, enabling absolute volume can lower the peak loudness, reducing audio dynamic range by up to 18 dB on some devices.

Not supported on all devices

Absolute volume is an Android feature that may not be supported on all Bluetooth devices. It requires cooperation from the phone OS, Bluetooth stack, and headphone/speaker hardware. Older devices or audio equipment may not work properly with absolute volume enabled, as noted in this ScreenRant article. Users report issues like volume control not working correctly with absolute volume on.

Recommended Absolute Volume Settings

There are a few guidelines for ideal absolute volume settings depending on your listening environment:

For mobile devices like smartphones and tablets, experts generally recommend setting the absolute volume to around 50-75% maximum. This keeps the volume at safe listening levels for headphones while still allowing you to hear clearly. Maximum peak levels on mobile devices should not exceed 85 decibels.

On desktop computers and laptops, the recommended absolute volume setting is around 40-60% maximum. Due to larger and more powerful speakers, desktops and laptops can produce higher volumes which can damage hearing at high levels. Peak volumes should stay below 100 decibels.

For home theater systems, absolute volume depends on room size but generally should be set to 75-85% maximum during normal listening. Loud peaks when watching movies or playing games should not go above 105-110 decibels to avoid potential hearing damage over time.

It’s also advisable to take breaks and avoid prolonged exposure to loud volumes, even if within recommended limits. Setting absolute volume levels appropriately for your environment is important for hearing health.

Platform Support for Absolute Volume

Absolute Volume is supported on Android devices running Android 6.0 Marshmallow or later versions of the Android operating system, according to the Android Open Source documentation. It works over the A2DP Bluetooth audio profile and allows the audio source device to directly control the volume rather than the playback device.

On Android, Absolute Volume is enabled by default but can be disabled in the Developer Options settings. It is supported in apps and browsers that use the standard Android audio playback APIs. Absolute Volume is not supported on iOS or earlier versions of Android.

For Windows 10 platforms, Absolute Volume support depends on the specific Bluetooth adapter and driver version. Many adapters do not support it even on Windows 10. Absolute Volume is also not universally supported across different web browsers on Windows. Chrome and Edge may support it while Firefox does not.

Overall, Absolute Volume has widespread support on modern Android platforms but is still hit-or-miss on Windows and iOS devices. App and browser support also varies depending on whether they use native audio APIs that interact properly with the platform’s Bluetooth stack.

Alternatives to Absolute Volume

Although enabling absolute volume provides some conveniences, there are alternatives that allow for more control over volume normalization across tracks and sources. Three alternatives worth considering are ReplayGain, manual normalization, and compression.

ReplayGain is an open standard that analyzes audio files and stores the recommended volume adjustment in the file metadata. Media players that support ReplayGain read this metadata and automatically adjust playback volume track-by-track for a more consistent listening experience. ReplayGain allows per-track volume normalization without actually modifying the source audio data (Source).

Manual normalization involves using audio editing software to manually adjust volume on a per-track basis. This gives precise control over volume levels, but can be extremely time consuming for large libraries. Many audio players also allow manual volume adjustment during playback.

Compressors and limiters are dynamics processing tools that can be applied across tracks for louder, more uniform playback levels. However compression reduces dynamic range and can negatively impact audio quality if overused. Light compression can be a good compromise between absolute volume and dynamic range (Source).

Each alternative has tradeoffs but may suit specific use cases better than enabling absolute volume globally.

Absolute vs Relative Volume

The key differences between absolute and relative volume are:

  • Absolute volume sets the display level based on a fixed reference like decibels. For example, 0 dB indicates the maximum recommended volume level. As you lower the volume, it shows the decrease in dB from the reference 0 dB level. This gives you an objective measure of volume regardless of equipment.
  • Relative volume simply shows the volume level on a scale from 0 to 100 based on the hardware capabilities. So 100 may indicate maximum volume on one system but only moderate volume on another more powerful system.

According to this video, absolute volume is useful for calibrating audio equipment against an established standard like THX reference level. It also makes it easier to achieve the same loudness across different content and audio sources.

Relative volume is more intuitive for everyday listening since you know the percentage of full volume. It works fine unless you need to precisely calibrate loudness.


Some technology platforms provide an option to enable absolute volume for headphones and speakers. Absolute volume sets a fixed volume level that remains consistent no matter what signals are being encoded or decoded by the hardware.

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