Mohammad Heydari
Mohammad Heydari was a santur player and composer, and one of Hayedeh's primary collaborators. He set poems for her voice and brought the arranger Naser Cheshmazar in for the orchestral settings, and he described her technical command plainly: she knew when she had it and when she did not. After 1979 he left Iran, first for Italy and then Los Angeles, where he kept writing until his death in 2016.
The songbook with his name on it runs wide: Ghalbam Gereft and Bahar Bahar for Hayedeh, Meykhooneh bi Sharab and Bia Benevisim for Mahasti, Sobhet Bekheir Azizam and Mosafer for Moein, Del-e Man for Dariush. Hearing that list as one hand's work changes how the era sounds: several of the voices a guest might already know turn out to share a composer. He was trained in the radif, the classical repertory, and carried it into three-minute pop arrangements by way of the santur he played; the formality Hayedeh brought from avaz met a composer who knew exactly what she was carrying. It was Heydari who described the difference between Hayedeh and her sister Mahasti - the softer voice and the stronger one - as someone who had written for both.
