The example from /r/coding[1] is very nice to listen to:

    awk 'function wl() {
        rate=64000;
        return (rate/160)*(0.87055^(int(rand()*10)))};
    BEGIN {
        srand();
        wla=wl();
        while(1) {
            wlb=wla;
            wla=wl();
            if (wla==wlb)
                {wla*=2;};
            d=(rand()*10+5)*rate/4;
            a=b=0; c=128;
            ca=40/wla; cb=20/wlb;
            de=rate/10; di=0;
            for (i=0;i<d;i++) {
                a++; b++; di++; c+=ca+cb;
                if (a>wla)
                    {a=0; ca*=-1};
                if (b>wlb)
                    {b=0; cb*=-1};
                if (di>de)
                    {di=0; ca*=0.9; cb*=0.9};
                printf("%c",c)};
            c=int(c);
            while(c!=128) {
                c<128?c++:c--;
                printf("%c",c)};};}' | sox -t raw -r 64k -c 1 -e unsigned -b 8 - -d

[1]: https://www.reddit.com/r/coding/comments/48zvn4/bash_one_lin...

That's quite a delight for the ears. Reminds me of Stéphane Picq's work on the Dune computer game soundtrack, back in the early 90s. It had some similar sounds.

A triangle/sawtooth wave sounds nicer without any filtering or other effects. It's the only "elementary" waveform that I know of that doesn't sound earpiercingly harsh.