# Bass and Treble

### From Audacity Development Manual

Bass and Treble increases or decreases the lower frequencies and higher frequencies of your audio independently. It behaves just like the bass, treble and volume controls on a domestic stereo system.

  Accessed by: Effect > Bass and Treble...

## Bass (dB)

The amount of gain (amplification above 0 dB or attenuation below 0 dB) to bass (low) frequencies. Set this to a positive amount to boost the bass, or to a negative amount to reduce the bass. Bass gain is applied to frequencies lower than 1000 Hz, with the most gain being applied to frequencies about 100 Hz or lower.

## Treble (dB)

The amount of gain (amplification above 0 dB or attenuation below 0 dB) to treble (high) frequencies. Set this to a positive amount to boost the treble, or to a negative amount to reduce the treble. Treble gain is applied to frequencies higher than 1000 Hz, with the most gain being applied to frequencies above 10000 Hz.

## Volume (dB)

This increases or reduces the overall level by up to +/- 30 dB.

- Applying a boost to the bass or treble will tend to increase the overall level. As a result, the final level may be pushed so high that it distorts (clips). To avoid clipping, reduce the level by setting the Volume control lower.
- Reducing the bass or treble may make the final level too quiet. To compensate for the lower level, set the Volume control higher.

If both the treble and bass frequencies are increased and the overall volume lowered, the overall effect is a reduction in the middle frequencies. Similarly, reducing both the bass and treble and increasing the volume has an overall effect of boosting the middle frequencies.

## Link Volume control to Tone controls

When this is enabled (checked), adjusting either the Bass or Treble controls will automatically adjust the Volume control so as to lessen the change in the resulting output level.

Even when linking the Volume control, the overall output level may still change a little, depending on the frequency content and how much the bass or treble are changed. Therefore always check Playback Meter Toolbar for possible clipping when trying out different bass and treble settings. Even when linked, you can still adjust the Volume control independently of the tone controls.

## Technical details

Bass and Treble is a two-band Equalizer.

- The Bass control is a low-shelf filter with the half gain frequency at 250 Hz.
- The Treble control is a high-shelf filter with the half gain frequency at 4000 Hz.
- All slider controls have a gain range of +/- 30 dB.

The half gain frequency is the frequency at which the gain is half of the filter gain. For example, if the filter gain was +10 dB then the half gain frequency would be the frequency at which the gain is +5 dB. However for shelf filters the half gain frequency is typically a fixed frequency regardless of the amount of gain. For other types of filter it is more common to define the cutoff frequency as the frequency at which the gain is -3 dB.

## Real-time preview

This effect supports Real-time preview - effect settings can be changed while playing and listening to the result in real-time. Text-based button controls are provided as in the image above. The Enable checkbox acts like a live "Bypass" control. Uncheck the checkbox Enable to hear the audio without the effect applied, and recheck the box Enable to hear the effect applied at its current settings.

The Manage button accesses choices to add, delete, import or export presets for this effect and to set options for this effect. For details see Manage presets.

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