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.
  you should not rely on any information that tells you that the check isn't good after six months. Here's why: if a check is more than six months old, your bank has two o â¦ ptions, either it can refuse to honor the check because of its date, or it can honor the check if it is not aware that you don't want it paid. personal check for the Bank of America is generally valid for at least thirty days. In many cases, these personal checks are valid for up to ninety days from the date of iss â¦ ue. Rachel Carter.