You could use a SCSI2SD, those are silent (for obvious reasons 
)
Or i would get one of the small 7K2 RPM SCA hdd's, i have a 9.1GB compaq 7K2 drive in my LCII and it is almost silent
)Or i would get one of the small 7K2 RPM SCA hdd's, i have a 9.1GB compaq 7K2 drive in my LCII and it is almost silent