public Builder setVolumeGainDb(double value) {

      volumeGainDb_ = value;
      bitField0_ |= 0x00000008;
      onChanged();
      return this;
    }
<pre>
Optional. Input only. Volume gain (in dB) of the normal native volume
supported by the specific voice, in the range [-96.0, 16.0]. If unset, or
set to a value of 0.0 (dB), will play at normal native signal amplitude. A
value of -6.0 (dB) will play at approximately half the amplitude of the
normal native signal amplitude. A value of +6.0 (dB) will play at
approximately twice the amplitude of the normal native signal amplitude.
Strongly recommend not to exceed +10 (dB) as there's usually no effective
increase in loudness for any value greater than that.
</pre>

<code>
double volume_gain_db = 4 [(.google.api.field_behavior) = INPUT_ONLY, (.google.api.field_behavior) = OPTIONAL];
</code>

@param value The volumeGainDb to set.
@return This builder for chaining.
java-texttospeech/proto-google-cloud-texttospeech-v1beta1/src/main/java/com/google/cloud/texttospeech/v1beta1/AudioConfig.java