             let nfIndex = Int(round(frac * Element(numberField.count)))
             let tone = Element(exp2(numberField[nfIndex]))
             let lp2 = pow(2, ttOctaveFactor)
-            var f = tone * lp2 * frequencyAtMiddleC
+            var f = tone * lp2 * middleCFrequency
             
             f = (0...AKTuningTable.NYQUIST).clamp(f)
             

        return content[Int(noteNumber)]
    }
    // setter
    public func setFrequency(_ frequency:Element, at noteNumber: MIDINoteNumber) {
        content[Int(noteNumber)] = frequency
    }
    

        let regexStr = "(\\d+\\/\\d+|-?\\d+\\.\\d+|-?\\.\\d+|-?\\d+\\.|-?\\d+)"
        var regex:NSRegularExpression?
        do {
            regex = try NSRegularExpression.init(pattern: regexStr,
                                                 options: NSRegularExpression.Options.caseInsensitive)
        } catch let error as NSError {
            AKLog("ERROR: cannot parse scala file: \(error)")
            return noteArray
