The Echo 2 was a speech synthesizer card for the Apple 2 and Apple //c personal computers. The Echo 2 used the TMS5220

TMS5220

The Texas Instruments LPC Speech Chips are a series of speech synthesizer DSP ICs created by Texas Instruments beginning in 1978. They continued to be developed and marketed for many years, though the speech department moved around several times within TI, until finally the speech department...

 speech synthesis chip, which could accept either phonemes or raw LPC data, with resulting higher speech quality.

The Original Echo 2

The Echo 2 was a plug-in expansion card designed for the Apple 2 computer, and allowed applications to use speech synthesis. LPC (linear predictive coding

Linear predictive coding

Linear predictive coding is a tool used mostly in audio signal processing and speech processing for representing the spectral envelope of a digital signal of speech in compressed form, using the information of a linear predictive model...

) was the speech synthesis technology used, which allowed applications to encode speech data in a compact form. The Echo 2 used the TMS 5220 LPC Speech Chip which was popular in other speech synthesizers