Macintosh Audio Compression and Expansion Toolkit (MACE) was a package
of audio codecs as well as a version of the System 7-era Sound Manager
that could be installed on System 6 systems.
> To help remedy this problem, the Sound Manager includes a set of
> routines known collectively as Macintosh Audio Compression and
> Expansion (MACE). MACE enables you to provide more audio information
> in a given amount of storage space by allowing you to compress sound
> data and then expand it for playback. These enhancements are based
> entirely in software and require no specialized hardware.
>
> The audio compression and expansion features allow you to enhance
> your application by including more audio data. MACE also relieves
> some distribution problems by reducing the number of disks required
> for shipping an application that relies heavily on sound. MACE has
> made some kinds of applications, such as talking dictionaries and
> foreign language-instruction software, more feasible than before.
>
> MACE adds three main kinds of capabilities to those already present
> in the Sound Manager: audio data compression, real-time expansion
> and playback of compressed audio data, and buffered expansion and
> playback of compressed audio data.
>
> Compression. The Sound Manager can compress a buffer of digital
> audio data either in the original buffer or in a separate buffer. If
> a segment of audio data is too large to fit into a single buffer,
> your application can make repeated calls to the compression routine.
> Real-time expansion playback. The Sound Manager can expand
> compressed audio data contained in a small internal buffer and play
> it back at the same time. Because the audio data expansion and
> playback occur at the same time, there is more of a strain on the
> CPU when using this method of sound expansion rather than buffered
> expansion.
> Buffered expansion. The Sound Manager can expand a specified buffer
> of compressed audio data and store the result in a separate buffer.
> The expanded buffer can then be played back using other Sound
> Manager routines with minimal processor overhead during playback.
> Applications that require screen updates or user interaction during
> playback (such as animation or multimedia applications) should use
> buffered expansion.
> MACE provides audio data compression and expansion capabilities in
> ratios of either 3:1 or 6:1 for all currently supported Macintosh
> models, from the Macintosh Plus forward. The principal tradeoff when
> using MACE is that the expanded audio data suffers a loss of
> fidelity in comparison to the original data. A small amount of noise
> is introduced into a 3:1 compressed sound when it is expanded and
> played back, and a greater amount of noise for the 6:1 ratio. The
> 3:1 buffer-to-buffer compression and expansion option is well suited
> for high-fidelity sounds. The 6:1 buffer-to-buffer compression and
> expansion option provides greater compression at the expense of
> lower-fidelity results and is recommended for voice data only. This
> technique reduces the frequency bandwidth of the audio signal by a
> factor of two to achieve the higher compression ratio.
> MACE allows for the compression of both monophonic and stereo
> sounds. However, some Macintosh computer models (such as the
> Macintosh Plus and Macintosh SE) cannot expand stereo sounds.
\- Inside Macintosh: Sound, Chapter 2
MACE was probably included on several developer CDs but this version
was a two floppy set that was available separately from ADPA
