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beep tool is explicitly designed to use the beeper only.
echo -e '\007' uses whatever bell effect your terminal emulator is configured to do: on the text-mode console, it typically uses the beeper. In a GUI desktop terminal window, the terminal emulator might have its own configurable beep sound, or it might use the desktop environment's default beep effect, which is usually configurable in the sound settings of the desktop environment.
Having said that, it is sometimes possible to redirect the beeper's sound into the speakers. In order to do that, you need an integrated sound chip (as most modern systems have), with a specific ability to reroute the beeper sound (which is included in some but not all sound chips). To enable that feature in Linux, you'll need to access the sound mixer functions of the actual sound card, instead of the simplified version that you'll get normally if your system includes the PulseAudio subsystem.
For example, if you use the
alsamixer command with no options in a PulseAudio-enabled system, you may see the volume control of PulseAudio only. But if you explicitly specify the sound card to use with e.g.
alsamixer -c 0 to specify the first sound card/chip of the system, you'll get the full audio mixer settings.
If the list of available sound channels includes "Beep", "Digital Beep" or something like that, it would be the PC beeper redirection channel. It might be just an on/off switch setting, or an adjustable level setting, or both. If you enable/unmute the channel, the beeper's signal should be redirected to the sound chip and output through the normal speakers.
Note: if your system has this feature and you decide to use it, check the volume level of the beep before you reboot the system. If you enable the redirection and set it to full volume, the standard beep at reboot time may come through the speakers and get amplified to unexpected loudness.
(Yes, this happened to me once. Apparently the sound chip is not always fully reset at reboot, at least not until the OS startup has proceeded to load the sound drivers again.)