Frequency is measured in hertz (Hz). A person who has hearing within the normal range can hear sounds that have frequencies between 20 and 20,000 Hz. The most important sounds we hear every day are in the 250 to 6,000 Hz range.
An issue date was added, and cheques may not be valid a certain amount of time after issue. In the US and Canada a cheque is typically valid for six months after the date of issue, after which it is a stale-dated cheque, but this depends on where the cheque is drawn; in Australia this is typically fifteen months.
Report Abuse. Unless otherwise marked, checks go stale 6 months from the date on the check. US Treasury checks are marked as valid for one year however if your state refund check has not such markings it went stale back in September. You'll have to return it to the state and ask to have it reissued. Source(s): Used to work in the banking industry.