def tts(self, text, cache=0, voice='kal_diphone'):
        voices = """kal_diphone
        ked_diphone
        don_diphone
        rab_diphone
        voice_cmu_us_slt_arctic_clunits
        en1_mbrola
        us1_mbrola
        us2_mbrola
        us3_mbrola
        gsw_diphone  ;; not publically distributed
        el_diphone)"""
        hash = md5.new(text).hexdigest()
        filename = '/var/lib/asterisk/festivalcache/%s' % hash
        if cache and os.path.exists('%s.wav' % filename):
            return filename
        os.path.exists('%s.wav' % filename) and os.unlink('%s.wav' % filename)
        cmd = '/usr/bin/text2wave -F 8000 -o %s.wav -eval "(%s)"' % (filename,voice)
        sys.stderr.write(' ---xxx--- EXEC: echo %s | %s' % (text,cmd))
        sys.stderr.write('\n\n%s\n\n' % cmd)
        f = os.popen(cmd, 'w')
        f.write(text)
        f.close()
        return filename