Simple categories matching harmonic:

• sound,
• signal,
• creation,
• instrument,
• system,
• timbre,
• relationship,
• phenomenon,
• structure,

Members with property harmonic:

• guitar,
• essence,
• human_voice,
• voice_exchange,
• piano,
• flute,
• fugue_composition,
• temporal_distribution,
• drum,
• rope,
• piano_tone,
• electrical_motor,
• noise,
• background,
• angular_distribution,
• castanets,
• voice,
• descending_piano,
• tidal_wave,
• diamond,
• electric_guitar,
• acoustic_instrument,
• bell_sound,
• bass_violin,
• medieval_mode,
• synthesiser,
• scale,
• speech,
• keyboard,
• background_music,
• accordion,
• electric_power,
• violin,
• voiced_speech,
• guitar_string,
• speech_signal,
• pentatonic_scale,
• bass,
• click,
• mode,
• music,
• vowel,