Connecting a USB Speaker to a Raspberry Pi to Convert Text to Speech and Have It Talk

ToC

• Overview
• Environment
• Connecting the USB Speaker
  • Check the card number and device number of the connected USB speaker
  • Test whether sound can be heard from the speaker
• Playing sound from a Python script
• Generating an audio file from text and reading it aloud

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Overview

Motivated by the idea of “Let’s have English conversations through a Raspberry Pi and OpenAI!”,
as a first step I made it read out specified text through a USB speaker.

Environment

I’m using the Raspbian OS that came preinstalled with the Marstudy Raspberry Pi 4 Model B Starter Kit.

$ cat /etc/os-release

PRETTY_NAME="Raspbian GNU/Linux 10 (buster)"
NAME="Raspbian GNU/Linux"
VERSION_ID="10"
VERSION="10 (buster)"
VERSION_CODENAME=buster
ID=raspbian
ID_LIKE=debian
HOME_URL="http://www.raspbian.org/"
SUPPORT_URL="http://www.raspbian.org/RaspbianForums"
BUG_REPORT_URL="http://www.raspbian.org/RaspbianBugs"

Connecting the USB Speaker

I’m using the Sanwa Supply Compact PC Speaker MS-P08UBK.

When I bought it on 2023-05-10, it was ¥857.

Check the card number and device number of the connected USB speaker

$ aplay -l
**** ハードウェアデバイス PLAYBACK のリスト ****
カード 1: Headphones [bcm2835 Headphones], デバイス 0: bcm2835 Headphones [bcm2835 Headphones]
  サブデバイス: 8/8
  サブデバイス #0: subdevice #0
  サブデバイス #1: subdevice #1
  サブデバイス #2: subdevice #2
  サブデバイス #3: subdevice #3
  サブデバイス #4: subdevice #4
  サブデバイス #5: subdevice #5
  サブデバイス #6: subdevice #6
  サブデバイス #7: subdevice #7

• Card number = 1
• Device number = 0

Test whether sound can be heard from the speaker

// plughw:<card>,<device>
$ speaker-test -D plughw:1,0 -t wav

// Stop and exit with Ctrl+c

Playing sound from a Python script

$ pip3 install pygame

$ curl https://www.soundjay.com/buttons/button-3.mp3 -o button.mp3

• play_sound.py

import pygame


def play_sound_file(file_path):
    pygame.mixer.init()
    pygame.mixer.music.load(file_path)
    pygame.mixer.music.play()

    while pygame.mixer.music.get_busy() == True:
        continue

if __name__ == "__main__":
    play_sound_file('button.mp3')

Running the following confirms that the mp3 is played.

$ python3 play_sound.py

Generating an audio file from text and reading it aloud

• speech.py

$ pip3 install gTTS
$ pip3 install pydub

from gtts import gTTS
from pydub import AudioSegment
from pydub.playback import play
import sys


def speechja(stext):
    tts = gTTS(stext, lang="ja")
    tts.save("/tmp/out.mp3")

    sound = AudioSegment.from_mp3("/tmp/out.mp3")
    play(sound)


if __name__ == "__main__":
    msg = "はい、お元気ですか？"
    speechja(msg)

Running the following plays “はい、お元気ですか？” from the speaker.

$ python3 speech.py

That’s all.
I hope this is helpful.

Next time I’d like to write about the setup for speech recognition from a microphone.