getEnv {soundgen}

Get amplitude envelope

Description

Returns the smoothed amplitude envelope of a waveform on the original scale. Unlike seewave::env, this function always returns an envelope of the same length as the original sound, regardless of the amount of smoothing.

Usage

getEnv(
  sound,
  windowLength_points,
  method = c("rms", "hil", "peak", "raw", "mean")[1]
)

Arguments

sound

numeric vector

windowLength_points

the length of smoothing window, in points

method

'peak' for peak amplitude per window, 'rms' for root mean square amplitude, 'mean' for mean (for DC offset removal), 'hil' for Hilbert, 'raw' for low-pass filtering the actual sound

Examples

a = rnorm(500) * seq(1, 0, length.out = 500)
windowLength_points = 50
scale = max(abs(a))
plot(a, type = 'l', ylim = c(-scale, scale))
points(soundgen:::getEnv(a, windowLength_points, 'rms'),
       type = 'l', col = 'red')
points(soundgen:::getEnv(a, windowLength_points, 'peak'),
       type = 'l', col = 'green')
points(soundgen:::getEnv(a, windowLength_points, 'hil'),
       type = 'l', col = 'blue')
points(soundgen:::getEnv(a, windowLength_points, 'mean'),
       type = 'l', lty = 3, lwd = 3)