A head-mounted device can effectively manage heat while also managing noise output in a manner that reduces the user's perception thereof. For example, a support member extending across a flow channel can provide multiple sections with different profiles and/or cross-sectional dimensions within the flow channel. Each of the profiles and/or cross-sectional dimensions can generate tonal noises at different frequencies, so that the tonal noises generated are distributed across multiple frequencies to mask such tonal noises among broadband noises that are generated by the head-mounted device. Such a support member can be moveably positioned within the flow channel and rigidly coupled to other components of the head-mounted device. Such a support member can also be used to draw heat away from other components of the head-mounted device to be dissipated by the flow of air within the flow channel.