How do I list FFMPEG's audio formats?

I'm trying to ask FFMPEG for all the audio formats it can encode.

I can get a list of formats with ffmpeg -formats:

File formats: D. = Demuxing supported .E = Muxing supported -- D 3dostr 3DO STR E 3g2 3GP2 (3GPP2 file format) E 3gp 3GP (3GPP file format) D 4xm 4X Technologies E a64 a64 - video for Commodore 64 D aa Audible AA format files D aac raw ADTS AAC (Advanced Audio Coding)
...

This shows me formats that it can encode/decode, but it's impossible to tell which are audio formats and which are video formats.

I can get a list of codecs using ffmpeg -codecs:

Codecs: D..... = Decoding supported .E.... = Encoding supported ..V... = Video codec ..A... = Audio codec ..S... = Subtitle codec ...I.. = Intra frame-only codec ....L. = Lossy compression .....S = Lossless compression ------- D.VI.. 012v Uncompressed 4:2:2 10-bit D.V.L. 4xm 4X Movie D.VI.S 8bps QuickTime 8BPS video .EVIL. a64_multi Multicolor charset for Commodore 64 (encoders: a64multi ) .EVIL. a64_multi5 Multicolor charset for Commodore 64, extended with 5th color (colram) (encoders: a64multi5 ) D.V..S aasc Autodesk RLE D.VIL. aic Apple Intermediate Codec DEVI.S alias_pix Alias/Wavefront PIX image
...

This shows me a list of "codecs" and whether or not they are for audio/video, but these aren't formats and thus aren't suitable for using with the -f flag.

For example, here's an audio codec but it doesn't work:

DEA.L. speex Speex (decoders: libspeex ) (encoders: libspeex )

C:\test>ffmpeg -i uwu.mp3 -f speex out.x

[NULL @ 00000000025ca260] Requested output format 'speex' is not a suitable output format
out.x: Invalid argument

So how can I get a list of formats from this thing that tell me whether or not they are audio formats?

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