diff --git a/DESCRIPTION b/DESCRIPTION
index 51b1b83..0fdbcf3 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -1,6 +1,6 @@
 Package: hrep
 Title: Harmony Representations
-Version: 0.8.0
+Version: 0.9.0
 Authors@R: person("Peter", "Harrison", email = "pmc.harrison@gmail.com", role = c("aut", "cre"))
 Description: This package provides methods for representing and manipulating chord sequences.
 Depends: R (>= 3.4.0)
@@ -25,6 +25,7 @@ Imports:
     tuneR (>= 1.3.3),
     abcR (>= 0.0.0.9005),
     tibble (>= 1.4.2),
-    utils
+    utils,
+    glue
 RdMacros: Rdpack
 Remotes: pmcharrison/abcR
diff --git a/NAMESPACE b/NAMESPACE
index 1b071cd..3968a52 100644
--- a/NAMESPACE
+++ b/NAMESPACE
@@ -137,7 +137,7 @@ S3method(pi_chord_type,pi_chord)
 S3method(pi_chord_type,smooth_spectrum)
 S3method(pi_chord_type,sparse_spectrum)
 S3method(pitch,sparse_pi_spectrum)
-S3method(play_pluck,default)
+S3method(play_sox,default)
 S3method(plot,smooth_spectrum)
 S3method(plot,sparse_spectrum)
 S3method(plot,wave)
@@ -162,11 +162,13 @@ S3method(represent,default)
 S3method(represent,list)
 S3method(represent,vec)
 S3method(sample_rate,numeric)
-S3method(save_wav_pluck,coded_vec)
-S3method(save_wav_pluck,default)
-S3method(save_wav_pluck,fr_chord)
-S3method(save_wav_pluck,pi_chord)
-S3method(save_wav_pluck,vec)
+S3method(save_wav_sox,coded_vec)
+S3method(save_wav_sox,default)
+S3method(save_wav_sox,fr_chord)
+S3method(save_wav_sox,pi_chord)
+S3method(save_wav_sox,sparse_fr_spectrum)
+S3method(save_wav_sox,sparse_pi_spectrum)
+S3method(save_wav_sox,vec)
 S3method(sparse_fr_spectrum,default)
 S3method(sparse_fr_spectrum,list)
 S3method(sparse_fr_spectrum,pi_chord)
@@ -260,10 +262,10 @@ export(pi_chord)
 export(pi_chord_type)
 export(pi_to_pc)
 export(pitch)
-export(play_pluck)
+export(play_sox)
 export(represent)
 export(sample_rate)
-export(save_wav_pluck)
+export(save_wav_sox)
 export(sparse_fr_spectrum)
 export(sparse_pi_spectrum)
 export(sum_amplitudes)
diff --git a/NEWS.md b/NEWS.md
index d7b002f..5c476b5 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -1,3 +1,7 @@
+# hrep 0.9.0
+
+- Expanding sound synthesis capabilities.
+
 # hrep 0.8.0
 
 - Added methods for synthesising audio.
diff --git a/R/play-pluck.R b/R/play-sox.R
similarity index 58%
rename from R/play-pluck.R
rename to R/play-sox.R
index 59e84fd..7b6a956 100644
--- a/R/play-pluck.R
+++ b/R/play-sox.R
@@ -1,8 +1,8 @@
-#' Play sound (pluck)
+#' Play sound (sox)
 #'
-#' Plays a sound with a plucked timbre.
+#' Plays a sound using the command-line tool sox.
 #'
-#' The sound is synthesised using \code{\link{save_wav_pluck}}
+#' The sound is synthesised using \code{\link{save_wav_sox}}
 #' and saved to a temporary file, which is then played from the R session.
 #'
 #' @note
@@ -11,18 +11,18 @@
 #' must be installed and available on the command line,
 #' making available the commands \code{sox} and \code{play}.
 #'
-#' @param x Object to play (see \code{\link{save_wav_pluck}} for valid options).
-#' @param ... Further parameters to pass to \code{\link{save_wav_pluck}}.
+#' @param x Object to play (see \code{\link{save_wav_sox}} for valid options).
+#' @param ... Further parameters to pass to \code{\link{save_wav_sox}}.
 #'
 #' @export
-play_pluck <- function(x, ...) {
-  UseMethod("play_pluck")
+play_sox <- function(x, ...) {
+  UseMethod("play_sox")
 }
 
 #' @export
-play_pluck.default <- function(x, ...) {
+play_sox.default <- function(x, ...) {
   file <- tempfile(fileext = ".wav")
-  save_wav_pluck(x, file = file, ...)
+  save_wav_sox(x, file = file, ...)
   system(paste0("play ", shQuote(file)))
   file.remove(file)
 }
diff --git a/R/save-wav-pluck.R b/R/save-wav-pluck.R
deleted file mode 100644
index e79a968..0000000
--- a/R/save-wav-pluck.R
+++ /dev/null
@@ -1,60 +0,0 @@
-#' Save wav file (pluck)
-#'
-#' Saves object to a wav file using the 'pluck' timbre from sox
-#' (\url{http://sox.sourceforge.net/}).
-#'
-#' @note
-#' The command-line sound-processing program sox
-#' (\url{http://sox.sourceforge.net/})
-#' must be installed and available on the command line
-#' under the command \code{sox}.
-#'
-#' @param x Object to save; methods exist for individual chords
-#' and for vectors of chords (see \code{\link{vec}}).
-#' Chords are coerced to a \code{\link{pi_chord}} representation.
-#' @param file (Character scalar) Output file.
-#' @param chord_length (Numeric scalar) Length of each output chord, in seconds.
-#' @param ... Parameters passed to methods.
-#'
-#' @export
-save_wav_pluck <- function(x, file, chord_length = 1) {
-  UseMethod("save_wav_pluck")
-}
-
-#' @export
-save_wav_pluck.default <- function(x, ...) {
-  save_wav_pluck(pi_chord(x), ...)
-}
-
-#' @export
-save_wav_pluck.vec <- function(x, file, ...) {
-  files <- paste("chord-", seq_along(x), "-", sep = "") %>%
-    tempfile(fileext = ".wav")
-  for (i in seq_along(x)) save_wav_pluck(x[[i]], files[i], ...)
-  cmd <- c("sox", shQuote(files), shQuote(file)) %>% paste(collapse = " ")
-  system(cmd)
-  file.remove(files)
-}
-
-#' @export
-save_wav_pluck.coded_vec <- function(x, file, ...) {
-  save_wav_pluck(decode(x), file, ...)
-}
-
-#' @export
-save_wav_pluck.pi_chord <- function(x, ...) {
-  save_wav_pluck(fr_chord(x), ...)
-}
-
-#' @export
-save_wav_pluck.fr_chord <- function(x, file, chord_length = 1) {
-  checkmate::qassert(file, "S1")
-  checkmate::qassert(chord_length, "N1(0,)")
-  len <- sprintf("%.10f", as.numeric(chord_length))
-  freq <- sprintf("%.10f", as.numeric(x))
-  tones <- purrr::map_chr(freq,
-                          ~ sprintf('"|sox -n -p synth %s pluck %s"', len, .)) %>%
-    paste(collapse = " ")
-  cmd <- sprintf('sox --norm=-3 -m %s %s', tones, file)
-  system(cmd)
-}
diff --git a/R/save-wav-sox.R b/R/save-wav-sox.R
new file mode 100644
index 0000000..89730cb
--- /dev/null
+++ b/R/save-wav-sox.R
@@ -0,0 +1,141 @@
+#' Save wav file (sox)
+#'
+#' Saves object to a wav file using sox
+#' (\url{http://sox.sourceforge.net/}).
+#'
+#' @note
+#' The command-line sound-processing program sox
+#' (\url{http://sox.sourceforge.net/})
+#' must be installed and available on the command line
+#' under the command \code{sox}.
+#'
+#' @param x Object to save; methods exist for individual chords
+#' and for vectors of chords (see \code{\link{vec}}).
+#' Chords are coerced to a \code{\link{pi_chord}} representation.
+#'
+#' @param file (Character scalar) Output file.
+#'
+#' @param ... Parameters passed to methods.
+#'
+#' @rdname save_wav_sox
+#' @export
+save_wav_sox <- function(x, file, ...) {
+  UseMethod("save_wav_sox")
+}
+
+#' @export
+save_wav_sox.default <- function(x, file, ...) {
+  save_wav_sox(pi_chord(x), file, ...)
+}
+
+#' @export
+#' @rdname save_wav_sox
+save_wav_sox.coded_vec <- function(x, file, ...) {
+  save_wav_sox(decode(x), file, ...)
+}
+
+#' @export
+#' @rdname save_wav_sox
+save_wav_sox.pi_chord <- function(x, file, ...) {
+  save_wav_sox(fr_chord(x), file, ...)
+}
+
+#' @export
+#' @rdname save_wav_sox
+save_wav_sox.sparse_pi_spectrum <- function(x, file, ...) {
+  save_wav_sox(sparse_fr_spectrum(x), file, ...)
+}
+
+#' @export
+#' @rdname save_wav_sox
+#'
+#' @param timbre
+#' (Character scalar)
+#' Timbre to use for synthesizing tones.
+#' Only applies to representations that have not already undergone
+#' harmonic expansion.
+#' This parameter is passed to the \code{type} argument of
+#' the \code{sox synth} command.
+#' Valid values include
+#' sine, square, triangle, sawtooth, trapezium, exp, noise,
+#' tpdfnoise, pinknoise, brownnoise, pluck.
+save_wav_sox.fr_chord <- function(x, file, timbre = "pluck", ...) {
+  save_wav_sox(
+    .sparse_fr_spectrum(frequency = as.numeric(x),
+                        amplitude = rep(1, times = length(x))),
+    file = file,
+    timbre = timbre,
+    ...
+  )
+}
+
+#' @export
+#' @rdname save_wav_sox
+#'
+#' @param reverb
+#' (Numeric scalar)
+#' Reverberance parameter for \code{sox reverb},
+#' expressed as a percentage.
+save_wav_sox.vec <- function(x, file, reverb = 20, ...) {
+  files <- paste("chord-", seq_along(x), "-", sep = "") %>%
+    tempfile(fileext = ".wav")
+  for (i in seq_along(x)) save_wav_sox(x[[i]], files[i], ...)
+  cmd <- c("sox", shQuote(files), shQuote(file),
+           "reverb", reverb) %>%
+    paste(collapse = " ")
+  system(cmd)
+  file.remove(files)
+  invisible()
+}
+
+#' @export
+#' @rdname save_wav_sox
+#'
+#' @param chord_length
+#' (Numeric scalar)
+#' Chord length (seconds).
+#'
+#' @param rise_length
+#' (Numeric scalar)
+#' Chord fade-in time (seconds).
+#'
+#' @param fade_length
+#' (Numeric scalar)
+#' Chord fade-out time (seconds).
+#'
+#' @param spectrum_gain
+#' (Coerced to character scalar)
+#' If "auto", then the chord's audio output is peak-normalised to
+#' a fixed value (using "--norm=-3" in sox).
+#' Other values will be passed directly to the "gain" parameter in sox.
+#'
+#' @param volume
+#' (Numeric scalar)
+#' Amplitude multipler (higher values make the sound louder).
+#' Only relevant when \code{spectrum_gain} is not \code{auto}.
+#'
+save_wav_sox.sparse_fr_spectrum <- function(x,
+                                            file,
+                                            chord_length = 1,
+                                            rise_length = 0.01,
+                                            fade_length = 0.01,
+                                            timbre = "sine",
+                                            spectrum_gain = "auto",
+                                            volume = 0.1,
+                                            ...) {
+  stopifnot(length(spectrum_gain) == 1)
+  fade_length <- fade_length
+  frequencies <- freq(x)
+  if (timbre == "pluck" && any(frequencies > 4000))
+    stop("cannot play plucked notes with frequencies greater than 4,000 Hz")
+  amplitudes <- amp(x) * volume
+  tone_cmd <- purrr::map2_chr(frequencies, amplitudes, function(fr, amp) {
+    '-v {amp} "|sox -n -p synth {chord_length} {timbre} {fr}"' %>%
+      glue::glue()
+  }) %>% paste(collapse = " ")
+  norm_cmd <- if (spectrum_gain == "auto") "--norm=-3" else ""
+  gain_cmd <- if (spectrum_gain == "auto") "" else paste0("gain ", spectrum_gain)
+  "sox {norm_cmd} -m {tone_cmd} {file} {gain_cmd} fade {rise_length} {chord_length} {fade_length}" %>%
+    glue::glue() %>%
+    system()
+}
diff --git a/man/play_pluck.Rd b/man/play_pluck.Rd
deleted file mode 100644
index f4b946f..0000000
--- a/man/play_pluck.Rd
+++ /dev/null
@@ -1,26 +0,0 @@
-% Generated by roxygen2: do not edit by hand
-% Please edit documentation in R/play-pluck.R
-\name{play_pluck}
-\alias{play_pluck}
-\title{Play sound (pluck)}
-\usage{
-play_pluck(x, ...)
-}
-\arguments{
-\item{x}{Object to play (see \code{\link{save_wav_pluck}} for valid options).}
-
-\item{...}{Further parameters to pass to \code{\link{save_wav_pluck}}.}
-}
-\description{
-Plays a sound with a plucked timbre.
-}
-\details{
-The sound is synthesised using \code{\link{save_wav_pluck}}
-and saved to a temporary file, which is then played from the R session.
-}
-\note{
-The command-line sound-processing program sox
-(\url{http://sox.sourceforge.net/})
-must be installed and available on the command line,
-making available the commands \code{sox} and \code{play}.
-}
diff --git a/man/play_sox.Rd b/man/play_sox.Rd
new file mode 100644
index 0000000..ab83af7
--- /dev/null
+++ b/man/play_sox.Rd
@@ -0,0 +1,26 @@
+% Generated by roxygen2: do not edit by hand
+% Please edit documentation in R/play-sox.R
+\name{play_sox}
+\alias{play_sox}
+\title{Play sound (sox)}
+\usage{
+play_sox(x, ...)
+}
+\arguments{
+\item{x}{Object to play (see \code{\link{save_wav_sox}} for valid options).}
+
+\item{...}{Further parameters to pass to \code{\link{save_wav_sox}}.}
+}
+\description{
+Plays a sound using the command-line tool sox.
+}
+\details{
+The sound is synthesised using \code{\link{save_wav_sox}}
+and saved to a temporary file, which is then played from the R session.
+}
+\note{
+The command-line sound-processing program sox
+(\url{http://sox.sourceforge.net/})
+must be installed and available on the command line,
+making available the commands \code{sox} and \code{play}.
+}
diff --git a/man/save_wav_pluck.Rd b/man/save_wav_pluck.Rd
deleted file mode 100644
index 8cbb7f2..0000000
--- a/man/save_wav_pluck.Rd
+++ /dev/null
@@ -1,29 +0,0 @@
-% Generated by roxygen2: do not edit by hand
-% Please edit documentation in R/save-wav-pluck.R
-\name{save_wav_pluck}
-\alias{save_wav_pluck}
-\title{Save wav file (pluck)}
-\usage{
-save_wav_pluck(x, file, chord_length = 1)
-}
-\arguments{
-\item{x}{Object to save; methods exist for individual chords
-and for vectors of chords (see \code{\link{vec}}).
-Chords are coerced to a \code{\link{pi_chord}} representation.}
-
-\item{file}{(Character scalar) Output file.}
-
-\item{chord_length}{(Numeric scalar) Length of each output chord, in seconds.}
-
-\item{...}{Parameters passed to methods.}
-}
-\description{
-Saves object to a wav file using the 'pluck' timbre from sox
-(\url{http://sox.sourceforge.net/}).
-}
-\note{
-The command-line sound-processing program sox
-(\url{http://sox.sourceforge.net/})
-must be installed and available on the command line
-under the command \code{sox}.
-}
diff --git a/man/save_wav_sox.Rd b/man/save_wav_sox.Rd
new file mode 100644
index 0000000..04f2ef4
--- /dev/null
+++ b/man/save_wav_sox.Rd
@@ -0,0 +1,79 @@
+% Generated by roxygen2: do not edit by hand
+% Please edit documentation in R/save-wav-sox.R
+\name{save_wav_sox}
+\alias{save_wav_sox}
+\alias{save_wav_sox.coded_vec}
+\alias{save_wav_sox.pi_chord}
+\alias{save_wav_sox.sparse_pi_spectrum}
+\alias{save_wav_sox.fr_chord}
+\alias{save_wav_sox.vec}
+\alias{save_wav_sox.sparse_fr_spectrum}
+\title{Save wav file (sox)}
+\usage{
+save_wav_sox(x, file, ...)
+
+\method{save_wav_sox}{coded_vec}(x, file, ...)
+
+\method{save_wav_sox}{pi_chord}(x, file, ...)
+
+\method{save_wav_sox}{sparse_pi_spectrum}(x, file, ...)
+
+\method{save_wav_sox}{fr_chord}(x, file, timbre = "pluck", ...)
+
+\method{save_wav_sox}{vec}(x, file, reverb = 20, ...)
+
+\method{save_wav_sox}{sparse_fr_spectrum}(x, file, chord_length = 1,
+  rise_length = 0.01, fade_length = 0.01, timbre = "sine",
+  spectrum_gain = "auto", volume = 0.1, ...)
+}
+\arguments{
+\item{x}{Object to save; methods exist for individual chords
+and for vectors of chords (see \code{\link{vec}}).
+Chords are coerced to a \code{\link{pi_chord}} representation.}
+
+\item{file}{(Character scalar) Output file.}
+
+\item{...}{Parameters passed to methods.}
+
+\item{timbre}{(Character scalar)
+Timbre to use for synthesizing tones.
+Only applies to representations that have not already undergone
+harmonic expansion.
+This parameter is passed to the \code{type} argument of
+the \code{sox synth} command.
+Valid values include
+sine, square, triangle, sawtooth, trapezium, exp, noise,
+tpdfnoise, pinknoise, brownnoise, pluck.}
+
+\item{reverb}{(Numeric scalar)
+Reverberance parameter for \code{sox reverb},
+expressed as a percentage.}
+
+\item{chord_length}{(Numeric scalar)
+Chord length (seconds).}
+
+\item{rise_length}{(Numeric scalar)
+Chord fade-in time (seconds).}
+
+\item{fade_length}{(Numeric scalar)
+Chord fade-out time (seconds).}
+
+\item{spectrum_gain}{(Coerced to character scalar)
+If "auto", then the chord's audio output is peak-normalised to
+a fixed value (using "--norm=-3" in sox).
+Other values will be passed directly to the "gain" parameter in sox.}
+
+\item{volume}{(Numeric scalar)
+Amplitude multipler (higher values make the sound louder).
+Only relevant when \code{spectrum_gain} is not \code{auto}.}
+}
+\description{
+Saves object to a wav file using sox
+(\url{http://sox.sourceforge.net/}).
+}
+\note{
+The command-line sound-processing program sox
+(\url{http://sox.sourceforge.net/})
+must be installed and available on the command line
+under the command \code{sox}.
+}